ACUTE CORONARY ACUTE CORONARY SYNDORME SYNDORME

EARLYEARLYRISK STRATIFICATIONRISK STRATIFICATION

Sarah JamisonMarch 2003

OverviewOverview

Definition of Acute coronary syndrome (ACS)

Factors used to determine risk stratification– History– Examination– ECG changes– Biochemical cardiac markers

– Initial management

Definitions – Definitions – Acute coronary Acute coronary syndromesyndrome

Any constellation of clinical symptoms that are compatible with acute myocardial ischemia.

It encompasses a spectrum fromAMI NSTEMI UA

NSTEMI – acute process of myocardial ischemia resulting in myocardial necrosis.The initial ECG does not show ST elevation

Definitions – Definitions – Acute coronary Acute coronary syndromesyndrome

UA – an acute process of myocardial ischemia that does not result in myocardial necrosis

Why be concerned re risk Why be concerned re risk stratification………stratification………

1) Are the symptoms a manifestation of ACS

2) Therapy/ site of care will vary dependent on diagnosis

3) To determine prognosis/short term survival

HISTORYHISTORY

History – diagnosing ACSHistory – diagnosing ACS

5 most important factors that relate to the likelihood of ischemia due to CAD…

– 1) Nature of the anginal symptoms– 2)Prior Hx of CAD– 3)Sex– 4)Age– 5)Number of traditional risk factors present

– Beware – women and elderly

History – diagnosing ACSHistory – diagnosing ACS

High – Chest/L) arm pain as chief symptom,similar to previous anginaKnown Hx of CAD (including MI)

Intermediate – Chest/L) arm pain as chief symptomAge>70yrs/Male/Diabetes

Low – Probable ischemic symptoms in absence of any of the intermediate likelihood characteristicsRecent cocaine use

History – short term risk of History – short term risk of death or nonfatal MI in unstable death or nonfatal MI in unstable anginaangina High – Accelerating tempo of ischemic

symptoms in preceding 48hrsPain – Prolonged ongoing (>20min) rest pain

Intermediate – Prior MI, peripheral or CVS/CABG/Aspirin usePain – Prolonged (>20min) rest angina, now resolved, with moderate or high likelihood of CAD.Rest angina (<20min) or relieved with rest or SL NTG

History – short term risk of History – short term risk of death or nonfatal MI in unstable death or nonfatal MI in unstable

anginaangina Low – New onset or progessive angina

(Marked limitiation/or inability to carry out any physical activity) over the past 2/52. Without prolonged (>20min) rest pain but with moderate or high likelihood of CAD

In patients that meet diagnostic criteria for UA/NSTEMI, the recent tempo of ischemic symptoms is the strongest predictor of risk of death

PHYSICAL EXAMINATIONPHYSICAL EXAMINATION

Examination - diagnosing ACSExamination - diagnosing ACS

High – Transient MR, hypotension,diaphoresis, pulmonary oedema

Intermediate – Extracardiac vascular disease

Low – Chest discomfort reproduced by palpation

Examination - short term risk of Examination - short term risk of death or nonfatal MI in UAdeath or nonfatal MI in UA

High – Pulmonary odema, most likely secondary to ischemiaNew or worsening MR murmurS3 or new/worsening creps

Hypotension / Bradycardia / TachycardiaAge > 75yrs

Intermediate – Age >70yrs

Examination - short term risk of Examination - short term risk of death or nonfatal MI in UAdeath or nonfatal MI in UA

Cardiogenic shock occurs in up to 5% of patients with NSTEMI and mortality rates are greater than 60%

THE ECGTHE ECG

ECG - diagnosing ACS ECG - diagnosing ACS

High – New, or presumably new, transient ST- segment deviation ( 0.05 mV) or T-wave inversion ( 0.2mV) with symptoms

Intermediate – Fixed Q waves / Abnormal ST segments or T waves not documented to be new

Low – T wave flattening or inversion in leads with dominant R waves / Normal ECG

ECG - diagnosing ACSECG - diagnosing ACS

A completely normal ECG in a patient with chest pain DOES NOT exclude the possibility of ACS.

- 1-6% of these patients it will be proven that they have had a NSTEMI

- 4% will be diagnosed with unstable angina

ECG - short term risk of death or ECG - short term risk of death or nonfatal MI in unstable anginanonfatal MI in unstable angina

High – Angina at rest with transient ST-segment changes > 0.05mVBundle – branch block, new or presumed newSustained ventricular tachycardia

Intermediate – T wave inversion >0.2mVPathological Q waves

Low – Normal/unchanged ECG during an episode of chest pain

ECG - short term risk of death or ECG - short term risk of death or nonfatal MI in unstable anginanonfatal MI in unstable angina

Risk factors ranked in order for risk of death in patients with ACS– 1) Confounding ECG patterns – bundle branch

pattern,paced rhythm, LV hypertrophy

– 2) ST segment deviation

– 3) Isolated T wave inversion or normal ECG

ECG pattern remains an independent predictor of death, after adjusting for clinical findings and biochemical cardiac markers

Biochemical cardiac Biochemical cardiac markersmarkers

Biochemical cardiac markersBiochemical cardiac markers

Useful in both the diagnosis of myocardial necrosis and estimation of prognosis

Prognosticaly there is a quantitative relationship between the magnitude of elevation of marker levels and the risk of an adverse event

BCM - diagnosing ACSBCM - diagnosing ACS

High – Elevated troponins or CK-MB

Intermediate – Normal

Low - Normal

A- myoglobin/CK-MB isoforms after AMIB – Cardiac Troponin after AMIC - CK-MB after AMID – Cardiac Troponin after UA

BCM - short term risk of death BCM - short term risk of death or nonfatal MI in unstable or nonfatal MI in unstable anginaangina

High – Elevated TnT > 0.1 ng/ml

Intermediate – Slightly elevated TnT (> 0.01 but <0.1 ng/ml)

Low - Normal

BCM – Creatine Kinase (CK-MB)BCM – Creatine Kinase (CK-MB)

Advantages - Rapid, cost- efficient accurate assays. Able to detect early reinfarction

Disadvantages – Loss of specificityLow sensitivity during very early MI (6hr after sxs onset) or later after sxs onset (>36hr) and for minor myocardial damage

BCM – CK-MB isoformsBCM – CK-MB isoforms

Advantages – Early detection of early MI (3-6hrs after onset of sxs)

Disadvantages – Specificity profile similar to that of CK-MBCurrent assays require special expertise (used predominately in research centers)

BCM - MyoglobinBCM - Myoglobin

Advantages – High sensitivityUseful in early detection of MI (2hrs after onset of sxs)Most useful in ruling OUT a MI

Disadvantages - Very low specificity in setting of skeletal muscle injury or diseaseRapid return to normal

Should not be used in isolation

BCM – Cardiac TroponinsBCM – Cardiac Troponins

Advantages - Powerful tool for risk stratification

Greater sensitivity and specificity than CK-MB

Detection of recent onset of MI up to 2 wks after onset

Useful for selection of therapy

BCM – Cardiac TroponinsBCM – Cardiac Troponins

Disadvantages - Low sensitivity in very early phase of MI (< 6hrs after onset of sxs) and requires repeat levels

Limited ability to detect late minor reinfarction

BCM – Other markersBCM – Other markers

CRP – Patients without biochemical evidence of myocardial necrosis but who have an elevated CRP are at an increased risk of an adverse outcome

Other – Elevated levels of interleukin-6, serum amyloid A, have similar predictive value as CRP

Putting it together - Putting it together - managementmanagement

Assign patients with chest pain to 1 of 4 groups– 1) Noncardiac

– 2) Chronic stable angina

– 3) Possible ACS

– 4) Definite ACS

Putting it togetherPutting it together

Most important baseline features assoc with death (Boersma et al)

AgeHeart rateSystolic BPST- segment depressionSigns of heart failureElevation of cardiac markers

Putting it togetherPutting it together

7 point risk score (Antman et al)

Age (>65yrs)More than 3 coronary risk factorsPrior angiographic coronary obstructionST – segment deviationMore than 2 angina events within 24hrsUse of aspirin within 7 daysElevated cardiac markers

ANY QUESTIONSANY QUESTIONS??????????????

SummarySummary

Risk stratification in ACS involves assessment of

HistoryExamination ECGBiochemical cardiac markers

Risk stratification is used in determining management and assessing prognosis

SummarySummary

High risk patients – 1.7% risk of death after 30 days

Intermediate patients – 1.2% risk of death after 30 days

Low risk patients – no death after 30 days