.H'JP—P» IMJI—H fflf

IfNClASSI^Iia) StCUWITV CLASSIFICATION OF THIS PAGE (Wh»n Oat« Enfrmd)

S r

CO o o <

REPORT DOCUMENTATION PAGE

fmr MBEF) 2. «BM»-*6««MI9W»»».

rjTLE r-«nd Suhtitl.l

A Clinical and Follow-up Study of Right and Left Bundle Branch Blocks y

■■■■H ■«■

^Kotman^ Michae nTiebwassef\ John H

MC , USAF, MC

9 PERFORMING ORGANIZATION NAME AND ADDRESS USAF School of Aerospace Medicine Aerospace Medical Division (AFSC) Brooks AFB, Texas 78235

II. CONTROLLING OFFICE NAME AND ADDRESS Internal Medicine Branch Clinical Sciences Division USAF School of Aerospace Med, Brooks AFB, TX

t* MONITORING AGENCY NAME A ADDHESSf/f d/r/«rsn( from Conlrotllng Otllc»)

1' * S^f »■».■-.-- M Uli..»«»- «-^■■.«■—

READ INSTRUCTIONS BEFORE COMPLETING FORM

a. w«riHtBMT'»q*Tftfc

■ TY^B'^^ HBPBWT.^

ER

COVERED

6. PERFORMING ORG. REPORT NUMBER

8. CONTRACT OR GRANT NUMBERf«;

'Jk^ääEF , PROJECT. TASK

AREA « WORK UNIT NUMBERS

17.

iu TWWIAM ELEMENT, AREA « WORK UNI1

12. REPORT DATE June 74

13. NUMBER 8

lot" y l ^tmrn^mmymp^^ .

URlTVCfc^llTTJ^IiWfM''*? 15. SEC

UM LV. 15» OECLASSIFICATION DOWNGRADING

SCHEDULE

16. DISTRIBUTION STATEMENT (ol ibl, Rtpott)

Approved for public release; distribution unlimited.

17. DISTRIBUTION STATEMENT (ol lh» mbttrmel »nfarad/n Block 20, II dllltrenl from Rtporl)

IB SUPPLEMENTARY NOTES

^ O r) (~*

It. KEY WORDS CConffnua on ravaraa afda ff nacaaaary and fdantffy by block number)

Right Bundle Branch Block Left Bundle Branch Block Morbidity Mortality Follow-up

^

** ^ L*j*

20. ABSTRACT (Cnnllruw on ravaraa afda ff nacaaaary and fdanr/fy by block numbar. The experience with bundle branch block at the USAF School of Aerospace Medicine was reviewed. The clinical and follow-up status was evaluated in 394 subjects with right bundle branch block (RBBB) and 125 subjects with left bundle branch block (LBBB). Most subjects were asymptomatic at the time of bundle branch block diagnosis. The subjects were divided into electrocardiographic (ECG) subgroups to determine if any one subgroup was at higher risk for initial or follow-up morbidity of cardiovascular disease or follow-up mortality. At initial diagnosis and clinical evaluation, 941 of RBBB subjects and 89? LBBB subjects had no

DD , ET« 1473 EDITION OF I NOV 65 IS OBSOLETE UNCLASSIFIED Sivc^Q T'V SECURITY CLASSIFICATION OF THIS PAGE (Wh»n Dafa Bnfarad;

\ UMCussma /

SECURITY CLASSIFICATION 0>' THIS PAGCftWi«« Oaf« Enl»nJ)

Block 20 (Continued) evidence ot cardiovascular disease. In the RBBB group, Z% and 2% had coronary heart disease and hypertension respectively; in the LBBB 9% and 7%. No one ECG subgroup in either the RBBB or LBBB group had a higher incidence of cardiovascular disease. Complete follow-up information was available in 94^ anc 91% of the RBBB and LBBB subjects respectively. The mean follow-up period was 10.8 * 4.7 years in the RBBB group and 8.8 + 4.8 in the LBBB group. In the follow-up period, new cases of coronary heart disease and hypertension occurred in 6% of the RBBB group and S% and 81, respectively, in the LBBB group. Four- teen (41) RBBB and 9 (8%)LBBB subjects expired during the follow-up period. No differences for follow-up morbidity of cardiovascular disease or mortality were observed in contrasting the individual ECG subgroups.

•

UNCLASSIFIED SECURITY CLASSIFICATION OF THIS PAGEflWi«! Dmlm Bnfr»d)

^m ^^

A Clinical and Follow-up Study of Right and Left Bundle Branch Block

HIJ MKHUI ROIMW, \1 \|()n, ISAF, MC!, wn JOHN M I'mt H\\ ASM H, COUJNEL, USAF, MC

SUMMAR\ / - The cxpcru'iur with luiiidlc hrancli hlmk at llii1 I SAF School "I Acrospini- Mcdiiuif was reviewed The clinical and fnl|nw-up status s\as evaluated in 'W4 subjects with tiuhl hmidle hralu h block I RBBB I and 125 siil>)e(ts with left bundk branch Mock (LBBB) The nw}orit) <it suhjeets were uymptcmiatic at the time of bundle branch block diagnasii The iubjecti were divided into itibgroupi bated on etectrwardk^raphic iK(!(ii Hndingt to determine if any one mbgroup was at higher riik for initial OT folhiw-up nwibkllty uf car- diovaicular disease or follow-up moitahtx \l initial diagnosis and elinieal evaluation, 9-4'. ol RBBB and 895i ol LBBB subjects had no evidenee of cardiovascular disease In the RBBB group, i and 2'r had cor- onarx heart disease and hypertension, respectively; in LBBB subjects, 9 and ~'i had coronarv heart disease and h\ pertension, respective|\ No one K( IG subgroup in either the RBBB or 1SSB group had a higher in- cidence ol cardiovascular disease Complete lollow-up information was available in 94'i ol the RBBB sub- jects and 91% ot the LBBB subjects The mean tollow-up period was 10.8 ±, 4 7 years in the RBBB group and H H-i; 4 S in the I.HUB Uronp In the lollow-up period, new cases of coronary heart disease and hvpertension occurred in 691 of the RBBB group and S and S'I . respectively, in the LBBB group, Fourteen (4ri ) RBBB and nine (H'I i LBBB subjects died during the follow-up period No differences for follow-up morbiditv of cardiovascular disease or mortality were observed in contrasting the individual FCC sub- groups Progitssive electrical dysfunction in the form ot complete heart block occurred in one subject each in the lUWh and I .IWI4 groups Thus the prognosis of bundle branch block is determined b\ the presence or absence, and degree ot associated cardiovascular disease Furthermore, within the age limits ot the present study, significant progressive electrical dysfunction is a rare occurrence The prognosis, etiology, and aeromedical implications of bundle branch block are discussed

Additional Incli-xing Words: Sudden death Flying status

-r >

THKCONCKPTOF Bl NDLK BRANCH BLOCK was introduced over HO years ago by Epplnger and

Rothberger in Vienna.1 A wealth "t literature related to the anatomy, electrophyslology, and clinical and prognostic lignificance of bundle branch block lias ac- cumulated since their original paper The most recent concept, proposed by Kosenhaum and his associates, of a trifascicnlar bundle branch conduction system, is clinically useful for diagnosis and prognosis.2 3

There is little agreement in the literature about the progtUMtk significance of bundle branch block.4 "1

Several factors account for the diHering results ob- tained in several other follow-up studies: different criteria in selecting patients, based on the electrocar- diograp'iic diagnosis of bundle branch block; dis- similar methods of grouping and presenting the available data, and most important, the population

From the Interral Medic me Bruich, (linical Sciences Dlvisian, I S\l- Scluxil ot Xerospiicc Mnllcinr .Xcrospa',* Medical Division, \1S( . t nilcd Stales Air Iorcc Hrooks Mr I'onc Base, Texas

I urlliei iipriicliic'lKiii is aullidri/i'cl to sal ist \ llic- needs lit llie IS Government

Vddrcss tor reprints John II Tnclmasser, drfonel, I SAF, MC, I s\ls\M S(.l Brooks \II Fon* Hase- Teus 78235

Received Si-iilrniliei i. 197-1. revision accepted lor piihilcalion O.tolM-r 21 ll»7l

(.mulaliun. liilume SI. Marm I9JS

base from which the electrocardiograms are obtained. Since tnost previous studies have studied the pattern in patients with overt disease, this last factor becomes important when attempts to compare and contrast the presence of bundle branch block in a clinically ill pop- ulation to that in an asymptomatic group are made.

The present study reviews the experience with patients with bundle branch block at the USAF School of Aerospace Medicine (I'SAFSAM) The pur- pose of the study was to group subjects with bundle branch block into various fascicular combinations and to compare and contrast these subgroups with regard to their clinical evaluation and follow-up status. A further comparison was made between the- group with right bundle branch block (RBBB) and the group with left bundle brand« block (LBBB)

Methods

The USAF Central EHectrocardiographic Library was es- tablished at I'SAFSAM in April 1957 The purpose of the librarv is to obtain and collect electrocardiograms (ECG)on all USAF rated Hying personnel and all applicants lor living or navigator tr lining The RCG librarv contains tracings on over 237,(KK) individuals The Aeromedical Consultation Service at I'SAFSAM evaluates all Hying personnel with medical problems Most aircrew members referred for evaluation are asymptomatic; a large proportion is referred because of I'X'.C, abnormalities

" " '' -

47H ROTMAN, TRIEBWASSER

In the pri'srnl stml\, .ill K( '(is referred to the K( X- lihrarx with a diagiMMii ot HHHH or LBBB during the years 1907 tlirmmli U)72 were roicssed The K(Xis «ere derived Irmn a l)elerii£eiieiMis group nf routine initial K('(js on in- di\i(liials less than 30 \ears nl age (including a mixed group (if Air Knree Academy cadets and applicants lor (UiriK train- ing) and serial l!(.(ls on rated flying personnel taken throughout tlieir Air Force career

Standard ECG criteria were used (or diagnoting RBBB ,iiid I lihH " Lett .interior hemiMock (LAH) was diagnosed according to the criteria o( Roaenbaum el alJ ' and included the following 1 I a mean (^HS axis of ö -45°, 2) small Q «a\es present in leads I and a\ i withaQiSi pattern. 3) nor- mal or slight prolongation o( QRS duration Simple le(t axis deviation (LAO) «as diannosed when the mean QRS axis was 2 SO* in the ahsenc«' o( criteria for LAH Since the diagnosis o( left posterior hemtUock is based on ■ combina- tion of clinical and ECG criteria.2 ' this diagnosis could not he justified in our retrospective analysis of the clinical evaluation Thus, the cases with riylit axis deviation (RAD) were divided into two groups; RAO > +120° and HAD of + 9()0 to H200 The diagnosis of 1° atrioventricular block (AVB) was made when the I'-R interval was ä 0 22 sec

In the majority of individuals. I SAFSAM carried out the initial clinical evaluation at the lime of diagnosis of RRRR or I hHli This evaluation included a history, physical examina- tion, routine ECX>, vectorcardiogram. and radionrapliic ex- amination of the chest l.ahoratorv evaluation Included a glucose tolerance test and determinations of serum cholesterol and triglycerides The Double Masters and treadmill exercise tests were used in exercise studies Furthermore, 54 subjects with RBBB and 29 with LBBB hod a complete cardiac catheleri/ation, Including selective cor- onary anglograph)

The follow-up study was accomplished usinn health records, (piestionuaires, and direct telephone com- munications The population that was critically examined included onlv those subjects that had had either an initial t Inuial evaluation and or available complete follow-up In- formation

The data was aualv/ed lor statistical significance by the biostatistics division at the School of Aerospace Medicine

Results

AfC Analvsis

From over 237.(KX) lubjects with ECCi in tht- ECG library (iurinn 1957-1972. a diagnosis of RBBB was made in 394 individuals and of I.BBB in 125 The age ranne at tim«' of diagnosis of th«1 BBBB group was 17 to 58 years, with a mean age of 36 ± 9 years. The I.BBB group bad an age rangt- of 20 to56 years, with a mean age of 40 ± 7 years (fig. 1). A significantly higher percentage of younger individuals (< 25 years old) was observed in the BBBB group, while a Inglier percentage of older individuals (> 45 years old) was noted in the I.BBB group (F < 0 001)

An analysis of variance was perfofined to determine it a significant difference in age was present between the ECG subgroups discussed below In the BBBB group there were significant differences between the mean ages (/' < 0.01) of the subgroup with normal axis (mean age of 34 ± 8 years) and the subgroup with

Si RBBB

N LBBB

30-34 35-39 40-44 45-49

»Gt GROUP IYEAHSI

Figure I

Agf ilt\lrihiili(in nt Mm* ol hmitllr linim li Mock dfagnotU HHHH in ilnrk Imrs. I.HUH in hatched liars .\ Hgntficant Ajfefenee

I' ■ (IIHII i uas (jhstrtcil in innlraslinn ihc Ino unities

BAD of +90° to +120° (mean age 31 ± H years). No other differences were observed In the I.BBB group, no significant differences were observed on age analysis between the three ECG subgroups.

FIcclriKurdidKraphji' Analysis

The ECG snbgrouping of subjects with BBBB is represented in table 1 A normal QRS axis was observed in 238 subjects (6! % ) An indeterminate axis was diagnosed in 45 subjects (11 % ) Bight axis devia- tion was noted in 76 subjects, with 59 (15'( | having a BAD of f90o to +120° and 17 (4%) with RAD of 120° Simple LAD was observed in H (2») subjects, while LAM was present in 20 (5fV ) subjects. In seven cases, 1° AVB was diagnosed, and five of fliese seven cases also had BAD +90° to +120° Table 2 presents the VX'.i) snbgrouping analysis in those subjects with I.BBB In these individuals, 97 (78« ) had normal C^BS axis, 25 l20'() had left axis deviation (> -30°), and three (2%) had 1° AVB,

In the ECG «'valuation, a diagnosis of BBBB was present on the first available ECG in 251 of the 394 cases. In the remaining 143 cases (37'( ), at least two KCCis without bundle branch block were available |)rior to the development ol RBBB In evaluating the

Table 1

I'Afctrorardiof'raphk Subgroup Amhjsis in 394 RBBB Subjects

Bubafoup \mnl>i Ptreent

Normal axis Imlelenniniili' axis liiKtil axis <120o

Hitdil axis >I2(»0

Siiiiplc left axis lieft anterior hamiblock 1° A-V block

338 4.-. 0!» 17

B 20

7 ;;'M

tu n i:.

IIKI

ClfeuMoH, Vohum }l, Manh 1973

L

FOLLOW-UP OF BBB 479

Tab!.- 2

Klcrtrorurdionraphic Subgroup Atudysis in 125 LBBB Subfectt

Siih^rotiii NomlifT IVrrrnt

Normiil axis

|y<'ft UM ilcviiiliiin

1° A-V l.l.Mk

97 2S

__3

m

7s 30

2

KM)

LBBB group, 14 of 120 cases had the ECG pattern of LBBB presenl on the first available ECG. In 81 (659! ) cases, LBBB was known to have been acquired <>n the basis of sampling serial yearly ECGs,

( liimal VnaUsit

Of the total 394 subjects with RBBB, 372 had a complete clinical evaluation at the time of diagnosis; 97r( were completely asymptomatic at the time of clinical evaluation A normal cardiovascular evalua- tion was present in 348 subjects (94r( ). Ten subjects (3K) had coronary heart disease; one had had a previous myocardial infarction, six had clinical evidence of coronary disease based on classic exer- tional chest discomfort, and three were asymptomatic but on selective coronary angiography had a greater than 509! obstruction of at least one major coronary artery. There were nine cases (2rf ) of mild to moderate hypertensive vascular disease, based on frequent blood pressure measurements wit4) averaged levels greater than 140/90 ram M^ Other forms of cardiovascular disease included five cases of con- genital heart disease (three with atrial septal defects, one with a patent dnctus arteriosns. and one with coarctation of the aorta and aortic stenosis), one case of rheumatic heart disease with mild mitral and aortic insufficiency, one case of documented myocarditis, and two cases of nonrheumatic hemodynamiially in-

Tuhle 3

.Si//)f,'r(»i/() Aniiltjsi\ of Clinical Evahtotion in EliliB Stihjcrts

significant mitral insufficiency. Since some of the ECG subgroups contained a small number of subjects, statistical testing comparing the subgroups was not performed; however, no individual ECG subgroup appeared to have a higher incidence of cardiovascular disease at the time of RBBB diagnosis (table 3).

Of the total 125 cases with LBBB, 121 had a com- plete cardiovascular evaluation at the time of diagnosis. 959! of the cases were asymptomatic A nor- mal evaluation was present in 101 subjects (89';r ) Eleven (99! I had coronary heart disease (seven on clinical evaluation and four by significant obstructive disease noted on coronary angiography). and eight (7rf ) had mild to moderate hypertension. One case each of rheumatic heart disease and of idiopathic car- diomyopathy were also observed. No ECG subgroup appears to have a higher incidence of cardiovascular disease (table 4).

In contrasting the initial clinical evaluation of the group with RBBB versus LBBB. a significantly higher number of cases of coronary heart disease (iJ < 0.01) and hypertension (P < 0.05) were observed in the LBBB group. This difference was not influenced by age factors since contrasting the two groups by age stratification still yielded significant differences.

I'dllowiip I'.valiiulinn

Complete follow-up information to June 1973 was available in 372 (94r, ) of the 394 cases with RBBB The remaining 22 cases were proportionally dis- tributed in the varied ECG subgroups 12 RBBB with normal axis; four RBBB with indeterminate axis; five RBBB and RAD; and one RBBB and simple LAH. Fourteen of the subjects lost to follow-up were less than 30 years old at the time of RBBB diagnosis, and 21 subjects were less than 40 years of age The mean follow-up period ot the RBBB group was 10.8 ± 4.7 years: 169! of the total group was followed for over 15 years; 575! over 11 years; 21c'( from six to ten years; and 16%, for less than six years.

In the LBBB group. 114 (91%) had complete follow-up information In the remaining 11 cases, seven had LBBB with normal iJWS axis and four had

Total Normal

N (111)

N 1IV1)

N

Subgroup Analysis

Tabl« 4

of Clinical Evaluat on in Niinnul utk 228 •214 ii 4 LBBB liulcU'iiniiiiilc axis 11 10 1 Subjects itixhl uxi.s <IW 56 51

15 i;

■ t 2

1 lütthl axis >ia0a

Simple ii'fi axis

Left anlciioi licrnililiick

Normnl Total N

CHD N

11VI) N

is It. l Normal axis <t:i H(l 1(1 3 1° A-V block 7 Q 1 Left axis (h'vialion 26 IN 1 .'i

N 372 ;MS 10 '.i 1" A-V block It 3 —

(%) (".»4) (3) (2) N 121 mi 11 H

At.i. :...;....■,".. \T i...... riur» i i (', ) (HID (91 ii i

dineaae; IIV1) ■ bypatsnnva vascular disease. Sec tabk :> for abbraviationM.

I mulaium. VohuHt SI, Manh 197}

480

LBBB with left axis dt-viation Tll^•<, Milijccts lost to

follow-up were K'ss than 30 years old at time of LBBB

diagnosis. The mean follow-up period was 8.8 ± 4 8

years: 9rf of the total Kr",1P Wi,s followed for over 15

years; 3691 over 11 years; 32'V from six to ten years;

and 3291 for less than six years.

The mean age at time of follow-up in the RBBB

group was 47 ± 10 years with an age range of 18 to 70

years The mean age in the LBBB group was 49 ± 7

years with an au;e range of 29 to Wi years (fin 2)

In the RBBB group during the follow-up period, 21

(ft'V ) new eases of coronary heart disease and 21 (69!)

new eases of hypertension developed; 14 (495)

patients died No one EGG subgroup appeared to be

at higher risk for follow-up morbidity of heart disease

or mortality (table 5),

In the LBBB group, six (5Ä ) now cases of coronary heart disease and seven (0rf ) new eases of hyperten-

sion developed; nine {HC/f ) subjects died Two new

cases of symptomatic idiopathic cardiomyopathy

developed during the follow-up period. No ECG sub-

groups seemed to be at higher risk for Follow-up mor-

bidity or mortality (table 6).

In contrasting the follow-up data on the RBBB and

LBBB groups by age stratification, no significant

differences were observed with regard to morbidity or

mortality. During the follow-up period for the ten subjects in

the HBBB group with coronary heart disease

diagnosed at the time of the initial evaluation, six

were asymptomatic, one had angina pectoris, one had

a nonfatal myocardial infarction, and two had died

(one of an acute myocardial infarction and one with

chronic !ung disease and cor pulmonale). Of the nine

BBBB subjects with an initial diagnosis of hyperten-

sion, seven were asymptomatic, one had congestive

heart failure and angina pectoris, and one died of an

acute myocardial infarction

During the follow-up period for the 11 subjects in

the I.BBB group with coronary heart disease

DRBBB

QLBBB

KO'IMAN. TRIEBWASSER

Table 5

n 14 14 13

n n,fi i IJLLJÜU ?ft .-*. /.i 30.14 .n ... 4(i 44 4'. 4'i S0.S4 BQ-SB «n-b4 0B

*t.l QMOUP (VKftnt)

Figure 2

i\ge (lislrihitluiu ul time of follouuii liliHIi tti liuhl Imn. I UliII in hatched han The nunilirr nf jmliinls itilhin CUI/I a§e group b pnnented above the bsn

Stihcrouji AiKilijsis of Followup F.tahmfion in RJWB Suhfecta

Total

NBW rni)

N

Ni.iv IfVI)

N 1 )<■«.!

N

Ndriniil iixis 220 If) II s [ndetwinimte BXü II 1 .i Itight axhi <120' ,-,l 2 2 liighl axis >12()'■ 17

Simple left sixi* H 1

\A'fi anterior bmiiblock 10 1

1° A-V l>lo<-k 7 1 1

N 372 21 21 n (%) ffi) (6) (*)

See Inlilc '4 for ahbrcvinlimis.

diagnosed at the time of initial evaluation, seven were

asymptomatic, one had angina pectoris, one had ex-

pired from an acute myocardial infarction, one was

lost to follow-up, and one had an acute myocardial in-

farction during which complete heart block developed

and necessitated permanent pacemaker implantation

Of the eight LBBB subjects with an initial diagnosis of

hypertension, three were asymptomatic, one had con- gestive heart failure and angina pectoris, one was lost

to follow-up, and three subjects expired (one, of an

acute myocardial infarction; one, of complications of

cardiac catheteri/ation; one of unknown causes).

The cause of death, as well as other relevant

parameters in the 14 RBBB patients who died, is

presented in table 7. in eight subjects the cause of

death was accidental; three died in aircraft accidents

related to bad weather, three died in automobile ac-

cidents, one fell off a scaffold, and one died of ac-

cidental carbon monoxide poisoning. Two subjects

died of pump failure during an acute myocardial in-

farction, one died of chronic lung disease complicated

In cor pulmonale. and for one, the cause of death was

not available.

Of the nine LBBB patients who died, five died of

conditions related to coronary heart disease: one

suddenly with a previous diagnosis of idiopathic car-

Tuble 6

Suhfiruiip Aiuib/sifi of l-'oUotvup Evahmtum in LBBB Subjects

Total (III) New 1IV1) Dead

Noriii.'il nxi.-. 90 ") 6 ti

Left MXIS ilcvini imi 21 1 i ■t

1° A-V 1)1.wk :t 1 N in 11 / g

('■, ) (8) (6) (8)

Sec table .'S for abbreviatioiu.

ClKuhUkm, VobuHf SI, March 1973

-• ^

FOLLOW-UP OF BBB 481

Tahlp 7

Atuihjsi.s of RHIili Suhjrrts Who Ditd During. Folloii-up Period

Aiir m

(yrartt) Snl.Krnup IIIJIIBI

fvaltifttutn

Koll(i«-u|j (lerjo'l (yvar*)

\Ki' ft» .If'Ulh

(year*) CaiiM oi •leaili

4<i Niiriiial axis Normal III .Mi Brain tumor 26 Ndriiial axi^ Normal to 36 Aiilo ai'ijdi'iit

t.i Noiiiuil nxis N'otiiia! 1 /SO l-nriK lurimr

II Normal axi>< HVI), CHI) 10 -.1 Myocardial infarction 33 Niimml nxis IIVD 3 .!li Arcidfnlal poMonin({

38 Normal axtB Normal 3 11 Aircraft acciilcnl

43 NiJiiniil nxis Normal 3 16 Unknown 32 Normal axi-. Ncirtnal 2 34 Aircraft aoridenl 39 Ind axis Normal 6 I.. Anio amdent 24 Iml axi-i Normal n 3") Airrraft aecidenl 35 Ind axis Normal g 1( Myocardial infarrtlon II RAD <I2(lü Normal ii 52 Afcidcnl

17 HAD <I2(I0 Normal i Is Audi Hccidcnt

.-.4 1° AVI? Clll) 14 6H l 'nr piilmonalc

iliii'iivopatlu. one of complications of cardiac cathctfri/ation, and tor two, the caiisr of death was unknown (table 8).

Dizzinen or lyncc^e rciatod to possible further electrical dysfunction ot the heart occurred in two patients with HBBH and one with LBBB. The two RBBB [)atieiits had syncopal episode's at a^es 55 and 50, five and einht years after the diagnosis of RBBB Both patients had normal initial evaluations. In one patient, complete heart block was documented and led to permanent pacemaker implantation. This patient had BAD +90° to +120° and 1° A\ B associated with his HBBB The other patient had one syncopal episode, which on thorounh investigation did not indicate heart block. This patient, who had BAD +90° to +120° associated with BBBB, is alive one year after his episode of syncope and remains asymptomatic. The single I,BBB patient had a perma- nent pacemaker inserted during hospitalization after an episode of syncope which occurred with an acute myocardial infarction and complete heart block. This

patient had coronary heart disease initially diagnosed at the time he developed I,BBB

Discussion

The majority of clinical studies noted in the literature dealing with the prognosis in subjects with bundle branch block portray an ominous outlook. The main reason for this prognosis is that these reports Usually come from a hospital-based population of generally ill patients. (Jraybiel and Sprague" reviewed ']95 cases with bundle branch block; most had cor- onary or hypertensive vascular disease. Iti their report, 118 cases fiad congestive heart failure; 59, angina pec- toris; and 12, Stokes-Adams syncope. A follow-up of 17'>( of the total group revealed 223 fatal cases, with an average life duration of 14 months Schrienivas et al" evaluated 2S1 cases of BBBB and noted that the prognosis was related to the presence and degree of cardiac disease. The worst prognosis in this series was tor patients with coronary and rheumatic heart dis- ease; the longest survival was for patients with no

Table 8

Analysis of LBRH SubfteH Who Dird Durinn the Follow-up Period

AKI' at cliaKlllIM»

(VHarn) Bubgroup IniliBl

evaltiHttun

Kotlon -U|> period (yeartO

Aue at ili'adi

(yvtirn) ('auN«" ot «leatli

:«» Normal udi Normal 12 AH Mvorardial infarction :;s Normal axi- MM) 7 45 CUD 4(1 Normal axi- IIVD 5 C, Myocardial infarction 45 Nornml axi-^ Normal A 30 Myocardial infarction 50 Normal axis Normal ■' 1 ."■ii Cardiac cath

40 Normal axis CUD III 50 Mvocardial infarction 37 LAI) Cardiomvopalliv ö 12 Sudden death 32 LAI) ll\ 1) 11 Hi Unknown 40 1° AVH Normal ■"> 40 Unknown

( inulalii»). i iilumr SI. Manh IV7S

f ■»

4 82 ROTMAN, TRIEBWASSER

defined etiology Inr the bundle branch block. Perera et al 4 studied 104 cases of RBBB. Of 91 eases with adequate tnllow-up, one-third had died over a mean follow-up period ol four years Over 95'V ol their patients had some form of heart disease in the same studv, a group of 60 cases with i iBBB were evaluated. 60S were dead at one year of follow-up Messer et al 7

noted in a review ol their hospitalized patients with Imndle branch block that the mean survival lor 281 RBBB and 555 LBBB cases was 3.9 and l:} years respectively Campbell* followed 50 patients with Imndle branch block (48 had some form of car- diovascular disease) 39 patients died, with a mean survival of two years

A few papen have dealt with subjects with Imndle branch block who were derived from an outpatient population or who had this defect discovered on routine examinations." '""■ l3 "■ 18" In 64 cases of RBBB, Wood et al " lound 35 with absent or minimal heart disease; 22 of these 35 cases remained asymp- tomatic over a two to 11 year follow-up period. Reush and Vivas"' found that only three of 38 subjects with RBBB and no diagnosed heart disease died during seven years of evaluation Smith et al 13 studied 24 naval aviators with acquired bundle branch block who were asymptomatic and had no evidence of car- diovascular disease They concluded that acquired bundle branch block is "frequently associated with a good prognosis in the asymptomatic patient. In a mortality study oil bundle branch block, Rodstein et al " present a group of individuals who were initially evaluated for purposes of insurability They found that the survival of the group without definite evidence of cardiovascular disease was "remarkably Hood Furthermore, they did not observe a "con- siderable difference in mortality statistics when com- paring the HRRB to the LBBB subjects.

This review of the literature couple'! with the pres- ent study elucidates the fact that the prognosis ol in- dividuals with bundle branch block is significantly determined by the presence or absence, and the degree, of associated cardiovascular disease.

The present study did not find a difference for mor- bidity of cardiovascular disease at time of diagnosis of bundle branch block or during the follow-up period between the ECG subgroups discussed; follow-up mortality also did not differ Thus, within the1 age limits of this study, the presence of unifascicular (RBBB with normal axis) or bifascicular (RRRR and I.All or LBBB) block did not affect prognosis. Though the prevalence of coronary heart disease and hypertension was significantly higher in the LBBB group, no significant differences were noted between the RRRR and LBBB groups with regard to follow-up morbidity or mortality.

The etiologic factors involved in subjects with RRR

and no clinically apparent cardiovascular disease may be important with regard to development ol further electrical dysfunction leading to complete heart block A number of processes can be postulated as possible etiologic factors In the younger population of RRRR patients, a disruption of this fascicle may have been present from birth, but no data is available relating to the incidence of RRRR iti normal and healthy in- fants.23, " It i;- important here to note that though the incidence of both RRRR and I,RRR increases with age, the incidence of RRRR below the age of 40 is eight times more frequent than l.RRR.'" 22 Furthermore, it is unusual to find an individual below the age of 30 with l.RRR In the present study, there were KM) patients in the RRRR group below age 30, compared to only 12 in the- l.RRR group Thus, in view of the rarity of I ,RRR in younger subjects and the know ledge that the majority of patients in the l.RRR group had acquired their conduction defect, a congenital etiology would indeed be unusual lor subjects with l.RRR

A clinically inapparent episode of myocarditis with residual impairment of intraventricular conduction may be an etiologic factor in both right and left bun- dle branch block subjects.2S-2e Two points support this hypothesis: first, the majority of patients in the pres- ent series with acquired bundle brunch block gave a history of a prolonged Hu-likv illness in the year preceding their ECG abnormality; secondly, angiographic and hemodynamic data on patients with acquired right and left bundle branch block with no clinically apparent cardiovascular disease have revealed a mild diffuse abnormality of the ventricular myocardium27,28 manifested by elevation of left ven- tricular end-diastolic pressure

In the older population, a degenerative process in or near the area of the conduction system seems to be a definite etiologic possibility.29,33 Careful pathologic studies of the conduction system by Vater,2' Lenegre,31

Lev,30 and Davles and Harris32 have revealed that in subjects above the age of 40, isolated involvement of the conduction system by degenerative fibrotic process, without significant involvement of the myo- cardium or other cardiovascular disease, is an impor- tant factor leading to bundle branch conduction de- fects and complete heart block. It is the consensus of some cardiac pathologists that this process is a result ol mechanical strain on the conduction system, lead- ing to "microtrauma of the proximal ramifications of the bundle branch system.30 33

Finally, in the present study, silent coronary artery disease may have also played an etiologic role: signifi- cant coronary artery disease was found in three (0r( ) of RRRR and four (1496) of l.RRR subjects who un- derwent cardiac catheteri/ation

Thus, it must be concluded that a number of

(inuluiion. KOAMIM SI, Manh 197S

.

FOLLOW-UP OF BB6 483

etiologic factors may be Involved In ihe developmeni dl iiitravt'iilrinilar conductton defecti in asymp- inmatii suhjcrts who an- free of clinicalK apparent cardimasinlar disease

In tlu- absence of cardiovaicular disease, the prognosis in subjects with bundle branch block relates to whether or not further electrical dysfunction and complete heart block develop Retrospective studies'4 ss in patients with complete heart block have revealed that in beats of supraventricular origin, some type of üiuiascicular or bifascicular involvement is present in the majority of these subjects. Prospective studies in patients with RBBB and LAM have found that the risk of developing complete heart block is in the range of 1091 to 16%.' 34 '" A higher number of patients (21%-75%) with RBBB and left posterior hemiblock are at risk for developing complete heart blocks3 •■'fl Complete heart block occurs most fre- (jueutly in men between 50 and 80 yean of age In the present study, only two patients had documented complete heart block, and in only one did syncope and complete heart block occur in the absence of car- diovascular disease. Some subjects with accidental deaths and some lost to follow-up, especially in the LBBB group, could have developed and/or possibly expired from the consequences of complete heart block; nevertheless, within the age limits of the pres- ent study, the risk of developing further electrical dysfunction was extremely low. A continued follow-up evaluation of the present population may identify a greater number who will develop further electrical dysfunction; it may also help to predict a high risk group for development of complete heart block

On the basis of this and previous studies on asymp- tomatic subjects with bundle branch block, certain criteria have evolved for the return of aircrew members, grounded because of K(.'(; abnormalities, to Hying status A number of USAF subjects with RBBB or LBBB have been maintained on Hying status (after a thorough cardiovascular evaluation that included hemodynamic, angiographic, and more recently, elec- trophysiologic studies) in the absence of objective evidence of cardiovascular disease."1 " We feel that this type of (borough evaluation is necessary to iden- tify aircrew members who are at low risk for sudden incapacitation

Refereiu-i-s

1 KITIM.MI II, Kmiim iii.ui CJ /.in Arial\M- Dei llcktrokar iliipuraiimis Wien Klin Wclmsilii 22: 10BI, KXH)

2 RcMENBA) M MB, EUZARI MV. 1,A//\HI JO The hciinhliKks Nc» (iiii(i'|)ts ill Intruvi'iitrkular COBduction liuscd on liuinan aiiatiiiiilcal. pliyMoliiKical, and cliiiitul stiuius Oidsmar, I lorida. TaMi|ia Truingi, 1970

3 ROMMHIM \lli Hit' JH'mililinks DiaKiKistii criteria and i Imkal Munilkaiicf Mod Cone CardtDvaic Dit Mi 141. 1!)70

I PEBKRACA, LEVINI SA, ERLAMCOI H Proxnosii of right bundle

(.inulaunn. Volume 51. March 1973

l.r.m.li lilmk A slndv (if KM cases Hr Heart J 4; V>. 1942 5 (anvmn 4, SPfMCVl HB Hntidli liraiK li l.lnik An unaKsis (i(

,195 cases Vm j Med Sei IS5: 395. 1933 h Siiiiiir\u\s. MeMER Al„ jdiisMis HP. WHITI I'D Prognoili

in bundle liranch lilnck I lactors inHuenciiiK ttie survival |ierl(«l m ri^lit linndlc liranch lilock \ni Heart J 40; S9I 1980

7 Mrssi ii \l,. liniMiM.ii wi \. Jiiiissos K|'. Si inn r\n \s. WHITI

I'D Pnigiuisis in bundle liranch hlcuk III A cnniparison of nulil .mil left liniidle lir.nii li lilock with a mite on the relative incidence ol each Am Heart J 41: 239, 1951

S WiKin FC, JIIUMS WA, Wininnii CC: Kcilldw-np stndv nl sijity-liiiir patients with a rinht bundle liranch conduction defect \iii Heart J 10: l()5h, 19a5

9 CAMPBCI.I M The oiitlmik with liniidle-liraiich hldck Bf Heart I 31; 575. 1969

in \ wiinui JP, I,HIM SA Benign bundle liranch block Arch Intern Vied S9: 5Hh, 1952

11 HdiisiHs M, GIBNER R, \IIIIS Jl', Lovr.l.l JF, I Mi m i inm III', \ niiirlajits stiid\ in linndlc branch tilnck Arch Intern Med HI: 663, 1951

12 K\ili(iK linndlc liranch lilock Sdine usual and sinne ninisiial feature! Anslralas Ann Med 1.3: H2, H»fi4

13 SMIIII HI', | si Ksiis DH, HvHiiioiiM J\\, SASHF.H» CA Acquired linndic liramh block in a health) population Am Heart J SO: 74(i, 1970

14 WOLFRAM J Bundle branch block without (ignificanl heart disease Am Heart J 41: 656, 1951

15 RM s< ii (IS, Vi\ ss JR Clinical analyiil dl rikiht bundle branch block. \m Heart J I8l 543, 1959

16 l.vM.in BW, Run JC, I i/ DC Hnndle branch block A review ol 1(H) cases Am Heart J 33: 730, 1947

17 (iiiwi Rl' Clinical electrocardiduraplu The spatial vector a|iprdacli Ne« York, Mctiraw Hill, 1957

IS Ri M n TB, GRAI M JG, PI U H RH Benign hit bundle branch block Ann Intern Med 70: 269. 1960

19 Mxssi\(,(;K, I.VSI (ITER MC Clinical lignificance of acquired complete rinht bundle branch block In 59 patients without overt cardiac disease Aerosp Med 40: 967, 1969

2(1 L*MB 1,1'., JOHNION Rl. Left bundle branch block in IKiliK personnel A report dl 56 cases Aemsp Med 35; 97. 1964

21 Jdiissus RL, \M mi i KH, LAMB IK Electrootrdlograidiic Rndings In 67,375 asymptomatic snbiects VI hi^hi bundle branch block Am j (ardiol «: 143. 1960

22 LAMR LE, K wo i Kl), Aviinii kit Electrocardiographic finding! in 67,375 asymptomatic snb)ci'ts \ Left bundle branch block \ni J (ardiol 6: 130. 1960

23 SUM ii n AR Rr.isi li I Ri^iit bundle branch sysJeni block in healthy young people Km Heart J «2: 487, 1961

24 CinkiM Jii Ccmgenital absence of the right branch of the linndlc of ffls Rr Heart J 13; 14S, 1951

25 Di UA CHAPELLI CE, KOSSM VNS (:K. Myocarditis Circulation 10; 747, 1954

26 SlLBEH EN, SAPHIB O Disease df the myiicardiiim /n Practice ol Medicine, edited by i,.i Hagentown, Md., W F Prior Co, Inc. 1959

27 LAKH yiTEB MC, Si in i mm E, MAISINC (ik Acquired complete right bnndle liranch block without overt cardiac disease Clinical and henidduianiic stiid\ ol 37 patients Am | (ardiol 30: 32. 1972

2s Si in i in in K, Finn I., LANCASTER M; Meaning irf acquired left bundle branch block Circulation 4« (suppl 11) 11-8, 1972

29 ^\IIII \\ Patbogenesis ol bundle branch block Arch Intern Med «2: 1, 1938

30 li \ \l Anatomic basis lor atriovenlrienlar bldck Am J Med 37: 742, 1964

31 l.isii.in J Etiolog) and pathology of bilateral bnndle branch

/s

4S4 ROTMAN, TRIEBWASSER

l>l"rk m rrljlmn tu irinplrli' liiarl lilcick I'mn Cardiovasc Dis fi: «W, I9»H

>^ DAV*EII M, HAinn A Pathologicalbasbof primw) hentMock lit llr.irl J M; 2H). 19()9

Vl Sii.nm M. ()nii\ R, kn>.i tu II. SIIIMI iiiiin () HinliilnKiial studies on lite inndiirttoii system in 14 'ases of rttltt limi<llr

liraneli block assmiateil wtttt left avis ileviatiiili Jap Heart J 1(1; 121, \mi

31 l.ssMii |U' II vt i Jl, Inn tun lie. (.(. Itelattiinship of nylit bittiille bratult lilnek and marked left axis devtatmii (with

'«

M.

left parietal or |>eri-ilifareti(iii IIIIM k I tii rumplete lieart lilmk and tynoopr Cimilatloii 37: 429. I9<JH

kit tit tins II. (:otiti.Mi\ I' Assneiatinn nf nullt liitndle

liraneli lilnek «ith left superior nr Inferior intraventricular block Its relation to complete heart lilnek and \dani Slnkes

syndrnme Hr Heart J 31i 435, 1969 Si wins I'J, rimm H, Ht in s t S(. JH Hi^ltt Inindle branch

lilnek assiK iated uitli left superior and inferior Intraven- trienlar lilnek Clinlca] setting, prntittnsis and relatinn to

complete heart lilnek Circulation 42: 1123. 1970

NT'S m$ iNfM c;c m hem ONAINOmCEl

nmmttusMMft

Mwmm mmumxr* mm

Circulalion, Volume J/, March I97J