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ADULT Minimally Invasive and Conventional Aortic Valve

Replacement: A Propensity Score AnalysisDaniyar Gilmanov, MD, Stefano Bevilacqua, MD, Michele Murzi, MD,Alfredo G. Cerillo, MD, Tommaso Gasbarri, MD, Enkel Kallushi, MD,Antonio Miceli, MD, and Mattia Glauber, MDDepartment of Adult Cardiac Surgery, G. Pasquinucci Heart Hospital, Gabriele Monasterio Foundation, Massa, Italy

Background. The study aimed to compare the short-term results of aortic valve replacement through mini-mally invasive and sternotomy approaches.

Methods. This is a retrospective, observational, cohortstudy of prospectively collected data on 709 patientsundergoing isolated primary aortic valve replacementbetween 2004 and 2011. Of these, 338 were performedthrough either right anterior minithoracotomy or upperministernotomy. With propensity score matching, 182patients (minimally invasive group) were compared with182 patients in conventional sternotomy (control group).

Results. After propensity matching, the 2 groups werecomparable in terms of preoperative characteristics.Cardiopulmonary bypass time (117.5 vs 104.1 min,p < 0.0001) and aortic cross-clamping time (83.8 vs 71.3min,p < 0.0001) were longer in the minimally invasive group,with no difference in length of stay (median 6 vs 5 days,p [ 0.43), but shorter assisted ventilation time (median

Accepted for publication April 29, 2013.

Address correspondence to Dr Gilmanov, Gabriele Monasterio Founda-tion, G. Pasquinucci Heart Hospital, 305, Via Aurelia Sud, Massa, MS54100, Italy; e-mail: drgilmanov@hotmail.it.

� 2013 by The Society of Thoracic SurgeonsPublished by Elsevier Inc

8 vs 7 hours, p [ 0.022). Overall in-hospital mortality wasidentical between the groups (1.64 vs 1.64%, p [ 1.0). Nodifference in the incidence of major and minor post-operative complications and related morbidity wasobserved. Minimally invasive aortic valve replacementwas associated with a lower incidence of new onset post-operative atrial fibrillation (21% vs 31%, p [ 0.04).Reduction of the complication rate was observed. Mediantransfusion pack per patient was higher in the controlgroup (2 vs 1 units, p [ 0.04).

Conclusions. Our experience shows that mini-accessisolated aortic valve surgery is a reproducible, safe, andeffective procedure and reduces assisted ventilationduration, the need for blood product transfusion, andincidence of post-surgery atrial fibrillation.

(Ann Thorac Surg 2013;96:837–43)� 2013 by The Society of Thoracic Surgeons

efinements in surgical techniques have reduced

Rmorbidity and mortality related to valve operations.Innovative, less invasive approaches for the surgicaltreatment of aortic valve disease were introduced withsuccess [1, 2]. Minimally invasive aortic valve surgery hasevolved into a well tolerated, efficient surgical treatmentoption in experienced centers, providing greater patientsatisfaction and lower complication rates [3, 4].

Potential advantages of minimally invasive aortic valvereplacement (MIAVR) arise from the concept that patientmorbidity and potential mortality could be reducedwithout compromising the excellent results of theconventional procedure and include improved cosmeticresults, safer access in the case of reoperation, less post-operative bleeding, fewer blood transfusions, lowerintensive care unit and in-hospital stays, as well as theabsence of sternal wound infection, and these resultswere achievable also in high-risk patients [5]. Reducedpain and hospital length of stay, decreased time untilreturn to full activity, and decreased blood product usehave also been demonstrated [6–8]. Most notable of all,

however, is the reduction in postoperative hemorrhageand transfusion requirements [9]. It has been difficult toconsistently demonstrate objective benefits to minimallyinvasive techniques for aortic valve replacement. Otherinvestigators have not been able to show any advantageto MIAVR approaches except a smaller incision [10]. Asprevious studies reached different conclusions andbenefits of MIAVR remain unclear, the aim of the presentstudy was to compare perioperative clinical outcomes,transfusion requirements, and early mortality in patientswho had MIAVR versus conventional aortic valvereplacement (AVR) in a consecutive large cohort ofpatients, using a propensity score matching analysis toadjust for potential differences between the 2 groups.

Material and Methods

Patient SelectionThe study was approved by the clinical audit committeeof the G. Pasquinucci Heart Hospital Institutional Boardto meet ethical and legal requirements, and individualconsent was waived. This was a retrospective, observa-tional, cohort study of prospectively collected data from709 consecutive patients with aortic valve disease whounderwent primary isolated AVR in our departmentbetween January 2004 and March 2011. Of these, 338

0003-4975/$36.00http://dx.doi.org/10.1016/j.athoracsur.2013.04.102

Abbreviations and Acronyms

AF = atrial fibrillationAVR = aortic valve replacementCAVR = conventional aortic valve replacementCI = confidence intervalCOPD = chronic obstructive pulmonary

diseaseCPB = cardiopulmonary bypassCVA = cerebrovascular accidentICU = intensive care unitMIAVR = minimally invasive aortic valve

replacementOR = odds ratio

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(47.7%) AVR were performed through either right ante-rior minithoracotomy or upper ministernotomy. Withpropensity score matching, 182 of them (MIAVR group)were compared with 182 patients receiving AVR in theconventional sternotomy (control group).

Allogeneic blood transfusions were considered trans-fusion of packed red blood cells, fresh frozen plasma,platelets, or whole blood. Any postoperative episode ofatrial fibrillation (AF) without history of previous supra-ventricular tachyarrythmiaswas classifiedasnewonsetAF.

Anesthetic, Surgical Technique, and PostoperativeManagementAnesthetic and surgical techniques were standardized forall patients and have been reported previously [11, 12].The MIAVR was performed through a 6 to 7 cm rightanterior (parasternal) thoracotomy in the second inter-costal space in 118 (64.8%) of 182 propensity matchedpatients and through ministernotomy in the remainder ofthe patients (n ¼ 64; 35.2%). The surgical technique ofV-shaped upper ministernotomy through the secondintercostal space was described elsewhere [11].

Choice of a specific minimally invasive approach forAVR in our institution depends on suitability of thepatient’s anatomy for right anterior minithoracotomy,

Fig 1. By computed tomographic scanimaging, patients are suitable for rightanterior minithoracotomy if at the level of themain pulmonary artery (A) the aorta isrightward (>50% of ascending aorta lies outof the right sternal border) and (B) thedistance between ascending aorta andthoracic wall is less than 10 cm. Vertical lineon (A) corresponds to right paramedian(parasternal) sagittal plane. Dashed lineshows ascending aorta anatomy unfavorablefor minithoracotomy. Arrow on (B) showsthorax depth – i.e., distance betweenascending aorta and thoracic wall.

which is our first-line approach. Chest computed tomo-graphic scan without contrast enhancement was per-formed for all patients considered for MIAVR.Patients were suitable for minithoracotomy if there

were the following at the level of the main pulmonarytrunk bifurcation, seen in transverse section: (1) morethan half of the ascending aorta was located on the rightside with relation to a vertical line drawn from the rightsternal border to the ascending aorta; and (2) the distancefrom the ascending aorta to the sternum (thoracic cavitydepth) did not exceed 10 cm (Fig 1).The majority of aortic procedures were performed with

normothermia or moderate cooling (32�C to 34�C), withwarm blood cardioplegia. Standard aortic valve replace-ment techniques were used with a pledgeted, interruptedsuture technique. Full median sternotomy approach inconventional AVR (CAVR) group was performedaccording to standard technique. All surgeries were per-formed by 8 senior surgeons of our department, with nodifference in operative technique, because uniqueinternal protocol was rigorously followed by them. At theend of surgery, patients were transferred to the intensivecare unit and managed according to the unit protocol.

Statistical AnalysisPatient demographic and operative data were summa-rized as mean � standard deviation, median with 25th to75th percentiles, or prevalence, as appropriate. TheKolmogorov-Smirnov test was used to check thenormality of data in the 2 groups before further analysis.The MIAVR and CAVR groups were compared using thec2 test for categoric variables and t or Wilcoxon rank sumtests, as appropriate, for continuous variables. To reducethe effect of selection bias and potential confounding inthis observational study, we developed a propensity scoreanalysis. All the variables listed in Table 1 were includedin the analysis. A propensity score, indicating the pre-dicted probability of receiving MIAVR treatment, wasthen calculated by the use of a non-parsimoniousmultiple logistic regression analysis from the logisticequation for each patient. Finally, we used the propensity

Table 1. Baseline Characteristics of the Entire Cohort and Propensity Matched Patients

Variable

All Patients Propensity matched patients

CAVR(n ¼ 371)

MIAVR(n ¼ 338) p Value

CAVR(n ¼ 182)

MIAVR(n ¼ 182) p Value

Age*, years 72.5 � 10.6 67.3 � 12.8 <0.0001 70.6 � 11.9 70.5 � 10.6 0.89Weight*, kg 72.5 � 13.9 75.2 � 13.4 0.001 73.6 � 13.4 74 � 14.3 0.98Height*, cm 163.8 � 9.2 168.7 � 9.1 <0.0001 166.2 � 9.3 166.5 � 9.3 0.82BMI*, kg/sq m 26.9 � 4.5 26.3 � 4 0.062 26.6 � 4.3 26.6 � 4.3 0.93Obesity (BMI > 29) 115 (31.0) 77 (22.8) 0.023 34 (18.7) 37 (20.3) 0.8Female gender 218 (58.8) 123 (36.4) <0.0001 88 (48.4) 87 (47.8) 1Functional class by NYHA* 2.5 � 0.7 2.1 � 0.8 <0.0001 2.27 � 0.72 2.29 � 0.75 0.89Dyslipidemia 228 (61.5) 215 (63.6) 0.6 117 (64.3) 114 (62.6) 0.81Smoking history 141 (38) 154 (45.6) 0.05 69 (37.9) 80 (44.0) 0.3Renal failure 21 (5.7) 14 (4.1) 0.45 10 (5.5) 9 (4.9) 1Diabetes mellitus 65 (17.5) 69 (20.4) 0.37 40 (22.0) 35 (19.2) 0.6Hypertension 308 (83) 239 (70.7) <0.0001 143 (78.6) 135 (74.2) 0.36Cerebrovascular disease 48 (12.9) 36 (10.7) 0.4 20 (11.0) 23 (12.6) 0.73Vascular disease 65 (17.5) 61 (18.0) 0.93 32 (17.6) 29 (15.9) 0.77COPD 72 (19.4) 45 (13.3) 0.04 25 (13.7) 25 (13.7) 1History of AF 72 (19.4) 50 (14.8) 0.13 37 (20.3) 33 (18.1) 0.69Ejection fraction* 0.548 � 0.101 0.566 � 0.079 0.01 0.556 � 0.101 0.562 � 0.083 0.57Ejection fraction < 0.30 9 (2.4) 4 (1.2) 0.34 6 (3.3) 2 (1.1) 0.29Urgent operation 52 (14.0) 33 (9.8) 0.1 23 (12.6) 21 (11.5) 0.87Logistic EuroSCORE I, mean (interquartile range) 6.6 (4.2–10.8) 4.5 (2.5–8.3) <0.0001 5.8 (3.5–9.6) 5.7 (3.1–9.8) 0.83

* - mean � SD.

Values are expressed as n (%) unless otherwise specified.

AF ¼ atrial fibrillation; BMI ¼ body mass index; CAVR ¼ conventional aortic valve replacement; COPD ¼ chronic obstructive pulmonarydisease; EuroSCORE I ¼ European System for Cardiac Operative Risk Evaluation, version I; MIAVR ¼ minimally invasive aortic valve replace-ment; NYHA ¼ New York Heart Association.

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score to match MIAVR to CAVR patients (1:1 match).Logistic regression modeling was used to identify inde-pendent risk factors for in-hospital mortality. Results arereported as percentage and odds ratios (ORs) and 95%confidence intervals. All reported p values are 2-tailed. Allstatistical analysis was performed with SPSS version 15.0(SPSS Inc, Chicago, IL).

Results

During the study period, 709 patients with aortic valvedisease underwent isolated AVR, of these, 338 patients(47.7%) had minimally invasive and 371 (52.3%) hadconventional surgery. After propensity score matchingthere were 182 matched pairs of patients (Table 1). In thematched cohorts, there was no longer any significantdifference between the 2 groups for any covariate.

Main clinical outcomes of propensity matched cohortsare presented in Table 2. Six (3.3%) cases with conversionto sternotomy in the MIAVR group were analyzed asintention-to-treat. Both cardiopulmonary bypass (CPB)time and aortic cross-clamping time were longer in theMIAVR group (p < 0.0001). For the entire propensitymatched population the proportion of cases with CPBtime more than 120 minutes and cross-clamping timemore than 90 minutes was significantly higher before

June 2008 (p ¼ 0.021 and p ¼ 0.043, respectively); mainlydue to gradual procedural improvements in MIAVRcohort in the second half of the study) (Table 3).Overall in-hospital mortality was identical between the

groups (p ¼ 1.0). Assisted ventilation time was lower inthe MIAVR group (p ¼ 0.022). No difference in hospitallength of stay (p ¼ 0.43), as well as in the prevalence ofpatients with prolonged postoperative length of stay (p ¼0.62) was revealed. An equal incidence of completeatrioventricular block requiring internal pacemakerimplantation (p ¼ 1.0) but a lower incidence of new onsetof postoperative AF (p ¼ 0.04) in the MIAVR group withan absolute risk reduction of 10% were observed.Incidence of neurologic events, pulmonary complica-

tions, and revision for bleeding was significantly lower(p ¼ 0.036) in patients operated after June 2008. Mediantransfusion unit per patient was higher in the controlgroup than in the MIAVR group (2 vs 1, respectively,p ¼ 0.04).The multivariable regression analysis showed the

duration of CPB over 110 minutes was an independentrisk factor for in-hospital morality (p ¼ 0.0344). Anotherindependent predictor of mortality was operative priority(p ¼ 0.0393) (Table 4).Interesting results were gained after further statistical

elaboration of the clinical outcomes data correlating

Table 2. Clinical Outcome of Propensity Matched Patients

Variables CAVR (n ¼ 182) MIAVR (n ¼ 182) p Value

CPB time, minutes 104.1 � 34.6 117.5 � 41.9 <0.0001Aortic cross-clamping time, minutes 71.3 � 27.5 83.8 � 28.5 <0.0001In-hospital mortality 3 (1.6) 3 (1.6) 1.0Assisted ventilation time, hoursa 8 (6–11) 7 (6–9) 0.022Assisted ventilation longer than 12 hours 33 (18.1) 23 (12.6) 0.2Assisted ventilation longer than 24 hours 9 (4.9) 4 (2.2) 0.27Low cardiac output syndrome 1 (0.5) 2 (1.1) 0.26New onset of AF 57 (31.3) 39 (21.4) 0.043Third degree atrioventricular block 2 (1.1) 2 (1.1) 1.0Permanent CVA (stroke) 4 (2.2) 2 (1.1) 0.69Transient CVA 1 (0.5) 1 (0.5) 1.0Hemodialysis 2 (1.1) 3 (1.6) 0.41Infective complications 5 (2.7) 4 (2.2) 0.28Pulmonary complications 8 (4.4) 10 (5.5) 0.58Pleural effusion requested drainage 5 (2.7) 10 (5.5) 0.19Reexploration for bleeding 11 (6.0) 8 (4.4) 0.63Revision for other reasons 2 (1.1) 5 (2.7) 0.45Blood transfusion pack per patient, unita 2 (0–3) 1 (0–2) 0.046Postoperative in-hospital length of stay, daysa 6 (5–7) 5 (5–6) 0.43Postoperative length of stay more than 6 days 53 (29.1) 48 (26.4) 0.62

a Median value (25th to 75th percentile).

Values are expressed as n (%) unless otherwise specified.

AF ¼ atrial fibrillation; CAVR ¼ conventional aortic valve replacement; CPB ¼ cardiopulmonary bypass; CVA ¼ cerebrovascular acci-dent; MIAVR ¼ minimally invasive aortic valve replacement.

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them to operating surgeon. Important inter-operatordifference in the total amount of performed cases wasrevealed; however, clinically important postoperativeevent and complication rates were not statistically diver-gent (Table 5).

Comment

Cardiac valve operations have historically been per-formed through a standard median sternotomy and CPB.But patients now demand less invasive procedures withequivalent safety, efficacy, and durability. New surgicaltechniques should lead to smaller incisions, less bloodloss, shorter hospital stays, and lower cost [13].

Table 3. Extracorporeal Circulation Data Dynamics During the S

Variable Ju

Entire propensity matched population (n ¼ 364)Cardiopulmonary bypass time, mina 11Aortic cross-clamping time, mina 8Cardiopulmonary bypass more than 120 minb 30Cross-clamping time more than 90 minb 24Minimally invasive aortic valve replacement cohort (n ¼ 182)Cardiopulmonary bypass more than 120 minb 26Cross-clamping time more than 90 minb 20

a Mean � standard deviation. b n (%).

Since early 1996, several surgeons have reported goodresults with minimal access approaches to the aortic valveduring cardiac operations [1, 4, 6, 7, 10, 14–18]. In January2004 we began our own series of minimally invasive aorticvalve surgery at the G. Pasquinucci Heart Hospital.Interim statistical analysis after an initial 50 case

series of MIAVR had shown several benefits of such anapproach regarding full sternotomy. So, an importantparadigm shift occurred in our department, and mini-mally invasive aortic valve surgery became our first-linestrategy. Sometimes, however, logistic or organizationreasons or intention to perform fast-track surgery madeus change operative tactics, preferring full sternotomy insuch cases.

tudy

Beforene 2008

AfterJune 2008 p Value

5.0 � 38 101.0 � 39 0.0014.1 � 28 72.4 � 26 0.0002(16.7%) 16 (8.7%) 0.021(13.3%) 13 (7.1%) 0.043

(32.5%) 13 (12.7%) 0.001(25.0%) 10 (9.8%) 0.006

Table 4. Multivariable Analysis of In-Hospital Mortality inPropensity Matched Patients

Variable OR

95% CI for OR

p ValueLower Upper

CPB duration more than110 minutes

4.11 1.35 27.3 0.0344

Urgent operation 3.2 1.17 52.7 0.0393

CI ¼ confidence interval; CPB ¼ cardiopulmonary bypass; OR ¼odds ratio.

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Currently, right anterior minithoracotomy is ourfavored surgical approach for AVR, to choose whenever itis technically possible. Upper V-type ministernotomy isconsidered second-line incision, and full sternotomyis a reserve type of surgical approach, the most rarelyperformed one and only in selected cases. Usually, thefinal decision upon operative plan, including surgicalapproach, is undertaken during the meeting beforesurgery and is a team-shared opinion that takes intoconsideration, mostly, the imaging data of chestcomputed tomographic scan and some contraindicationsfor a minimally invasive surgical approach (eg, previousright side pleural effusion with adhesions formation,severe chest wall deformities, or technical impossibility toobtain peripheral percutaneous venous cannulation).Thus, the choice of operative technique is a result ofapplication of our internal guideline recommendationsto a single patient, and is not a surgeon’s personalpreference.

In earlier reports, operative mortality was equalbetween minimally invasive and conventional proceduresfor aortic valve surgery [4, 7, 8, 14]; our case series also didnot reveal any difference in hospital mortality. In 2004,Mihaljevic and colleagues [16] showed a mortality rate of2% in the MIAVR group versus 3% with conventionalsternotomy. Another study reported lower incidence ofsepsis or wound complications, less fresh frozen plasmatransfusion, and a shorter length of hospital stay associ-ated with MIAVR [7].

Smaller incisions should theoretically reduce post-operative bleeding and transfusion requirements, notablywith the significant morbidity and mortality associatedwith transfusions and bleeding re-exploration [19]. Somestudies report no difference in transfusion requirements[6, 20], whereas others note fewer blood product trans-fusions with minimally invasive valve surgery. Severalstudies have reported a significant reduction in post-operative hemorrhage and transfusion requirements [14,21] and a notable decrease in postoperative chest tube

Table 5. Clinically Important Events and Complications Rate–Per

Operating surgeon “1” “2” “3”Performed cases, n 52 36 40Total of clinically important

events and complications, n (%)a7 (13.5) 3 (8.3) 8 (20.0)

a p ¼ 0.824 for interpersonal difference between operating surgeons.

output in the minimally invasive approach groupcompared with the conventional group [22]. Especially,a right thoracotomy was associated with 51% fewer bloodproducts than a conventional sternotomy [8]. Minimallyinvasive aortic valve surgery has acceptable incidence ofpostoperative bleeding necessitating reoperation [2, 23],comparable with the CAVR.Svensson and D’Agostino [24] described an average

transfusion amount of 0.86 U, which decreased to 0.3 Uin a subsequent study [24]. Cosgrove and colleagues [25]reported an average requirement of 1.1 U of red bloodcells with a parasternal approach. In a more recent study[14], 37.5% of the patients who had MIAVR requiredpostoperative transfusions compared with 62.5% of theCAVR group. In the current study, we sought to furthervalidate and supplement the previous reports. Of note,independent of risk adjustment by propensity matching,the need for blood transfusion was significantly lower inthe MIAVR group compared with controls.A small incision in the second intercostal space, in case

of right anterior minithoracotomy, merges well withfavorable orientation of the muscle layers, with nonecessity to transect muscular fibers. Nonetheless, inpatients with particular lateral location of a right internalthoracic (mammary) artery one might sometimes becompelled to isolate and surgically divide the vessel inorder to avoid intraoperative lesion and subsequenthemorrhage due to rib retraction. By our estimation, theright mammary artery was sacrificed in less than 10% ofcases (unfortunately, a precise value could not be derivedfrom our clinical database).Concern still exists about higher probability of neuro-

logic disorders after MIAVR. Physical limitations ofminimally invasive aortic valve procedures and inade-quate removal of air may theoretically lead to a higherincidence of neurologic complications, so that the use oftransesophageal echocardiography to minimize airemboli and stroke is mandatory.The present study shows that insufficient removal or air

and subsequent elevated rate of ischemic neurologiccomplications were effectively prevented by carbondioxide insufflation and the use of transesophageal echo-cardiographic control, resulting in a similar incidence ofpermanent and transient neurologic deficit between thegroups. Interestingly, 5 different studies reported nodifference in the incidence of stroke with minimallyinvasive heart surgery, whereas 2 [13, 16] found adecreased incidence with a minimally invasive approach.In our study, prolonged cross-clamp and cardiopul-

monary bypass times were noted in the MIAVR groupcompared with the conventional AVR group. Physically

sonal Surgical Performance

“4” “5” “6” “7” “8” Total32 118 24 22 38 364

2 (6.3) 15 (12.7) 4 (16.7) 3 (13.6) 5 (13.2) 47 (12.9)

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limited exposure and little space to operate were usuallythe reason. Besides, this study included initial series ofpatients with obvious effect on the learning curve. Indeed,the prevalence of patients with CPB over 120 minutes andcross-clamping time over 90 minutes has been reducedalmost twice in the second half of our practice since June2008. In the same way, significantly lower incidence ofneurologic events, pulmonary complications, and revisionfor bleeding was observed in the second period and can beexplained by the learning curve effect.

A similar prevalence of postoperative AF after MIAVRor mitral valve surgery compared with a matched controlgroup undergoing conventional sternotomy, even afterstratifying for valve type, was described earlier [26]. Wefound a 10% absolute risk reduction for new onset of AFin the MIAVR cohort. It has been demonstrated that rightminithoracotomy might be a protective factor against AFafter AVR [12].

Probably due to a small number of recruited patients, thecurrent study could not demonstrate shorter length ofhospital stay,wound infection, orneurologic complicationsin theMIAVR cohort. Another possible confounding causemay be the fact that 2 different minimally invasiveapproaches for aortic valve, right anterior parasternalminithoracotomy, and upper V-typeministernotomywereanalyzed together, while in our practice the first one isassociated with quite better surgical outcomes [12] (rightminithoracotomy, but not upper ministernotomy, is asso-ciated with lower incidence of postoperative AF, shorterassisted mechanical ventilation, and length of hospitalstay). Thus,we are convinced that in the setting of aMIAVRthe patient may expect to enjoy the above mentionedadvantages of a right minithoracotomy approach whentechnically possible. Even if due to an anatomic situation(relatively central retrosternal position of the ascendingaorta, profound thorax) or other reasons (pleural adhe-sions) that preclude a right minithoracotomy, urging anupper ministernotomy, a lower risk of blood transfusion,shorter mechanical ventilation time, and better cosmeticresult remain as possible rewards. For stentless valvularprostheses, a right minithoracotomy approach cannot beapplied and an upper ministernotomy remains the uniqueminimally invasive solution.

In summary, MIAVR is associated with a lower use ofblood products, postoperative new onset AF, and shortermechanical ventilation. A minimally invasive approachcan be safely performed for aortic valve surgery with thesame rates of morbidity and operative mortality.

This study is based on a retrospective analysis of ourlarge, institutional, observational, prospectively collecteddatabase; thus it reflects a single-center experience only.The short follow-up time (only until patient discharge)was a limitation of this study, as was the retrospectivemethodology. However, chart review and data entry wereperformed according to prespecified definitions, and dataanalysis was performed using propensity scores to adjustfor differences in preoperative risk factors. Propensityscore analysis is simply a method for reducing bias inobservational studies and the matching was limited byavailable variables. The present study lacked assessment

of postoperative pain as it is not included in our clinicaldatabase. Despite that the multivariable logistic regres-sion identified CPB duration over 110 minutes andurgency of surgery as independent predictors of in-hospital mortality, this analysis is limited by the lownumber of events (6 deaths) that could have affected theresult, as shown by a wide confidence interval. Weutilized all-cause mortality data, though reliably obtainedfrom our database, rather than the more specific cardiac-related mortalities and we did not address the relativeincidence of nonfatal cardiac-related events. The seriesalso encompasses our “learning curve,” as it includes ourinitial experiences with MIAVR.To conclude, in our experience, minimally invasive

isolated aortic valve surgery is a reproducible procedureas safe and effective as AVR through sternotomy, withsimilar morbidity and mortality, and reduces assistedventilation duration, the need for blood product trans-fusion, and incidence of post-surgery AF.

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ABTS Requirements for thefor Maintenance of Certifica

Diplomates of the American Board of Thoracic Surgery(ABTS) who plan to participate in the 10-Year Milestonefor the Maintenance of Certification (MOC) process asCertified-Active must hold an unrestricted medicallicense in the locale of their practice and privileges ina hospital accredited by the JCAHO (or other organiza-tion recognized by the ABTS). In addition, a valid ABTScertificate is an absolute requirement for entrance into theMOC process. If your certificate has expired, the onlypathway for renewal of a certificate is to take and passthe Part I (written) and the Part II (oral) certifyingexaminations.

The CME requirements are 150 Category I credits overa five-year period. At least half of these CME hours needto be in the broad area of thoracic surgery. Category IIcredits are not accepted. Interested individuals shouldrefer to the Board’s website (www.abts.org) for a completedescription of acceptable CME credits.

Diplomates will be required to take and pass a securedexam after their application has been approved. TakingSESATS in lieu of the secured exam is not an option. Thesecured exam is administered over a two-week period inSeptember of every year at Pearson Vue Testing Centers,which are located nationwide. Diplomates will have theopportunity to select the day and location of their exam.For the dates of the next MOC exam, visit the Board’s website at www.abts.org.

� 2013 by The Society of Thoracic SurgeonsPublished by Elsevier Inc

20. Yamada T, Ochiai R, Takeda J, Shin H, Yozu R. Comparisonof early postoperative quality-of-life in minimally invasiveversus conventional valve surgery. J Anesth 2003;17:171–6.

21. Bakir I, Casselman FP, Wellens F, et al. Minimally invasiveversus standard approach aortic valve replacement: a studyin 506 patients. Ann Thorac Surg 2006;81:1599–604.

22. Dogan S, Aybek T, Risteski PS, et al. Minimally invasive port-access versus conventional mitral valve surgery: prospectiverandomized study. Ann Thorac Surg 2005;79:492–8.

23. Soltesz EG, Cohn LH. Minimally invasive valve surgery.Cardiol Rev 2007;15:109–15.

24. Svensson LG, D’Agostino RS. “J” incision minimal-accessvalve operations. Ann Thorac Surg 1998;66:1110–2.

25. Cosgrove DM II, Sabik JF, Navia JL. Minimally invasive valveoperations. Ann Thorac Surg 1998;65:1535–8.

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10-Year Milestonetion

Starting on July 1, 2014, the ABTS will require itsDiplomates to participate in an outcomes database asfulfillment of Part IV (Performance in Practice) for the 10-year Milestone of Maintenance of Certification (MOC).For a list of approved outcomes databases or for moreinformation on how to have a database approved by theBoard, visit the Board’s website at www.abts.org. Partic-ipation in the Professional Portfolio will no longer beaccepted as fulfillment of MOC Part IV after July 1, 2014.Diplomates may apply for MOC in the year their

certificate expires or, if they wish to do so, they may applyup to two years before it expires. However, the newcertificatewill be dated 10 years from the date of expirationof their original certificate or most recent MOC certificate.In other words, going through theMOCprocess early doesnot alter the 10-year validation. Diplomates certified priorto 1976 (the year that time-limited certificates were initi-ated) are also required to participate in MOC if they wishto maintain valid certificates.The deadline for submitting an application for 10-year

Milestone of MOC is March 15 of every year. Informationoutlining the rules, requirements, and dates for MOC inthoracic surgery is available on the Board’s website atwww.abts.org. For additional information, please contactthe American Board of Thoracic Surgery, 633 N St. ClairSt, Ste 2320, Chicago, IL 60611; telephone (312) 202-5900;fax (312) 202-5960; e-mail: info@abts.org.

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