ACUTE CORONARY SYNDORME EARLY RISK STRATIFICATION Sarah Jamison March 2003

Overview Definition of Acute coronary syndrome (ACS) Factors used to determine risk stratification – History – Examination – ECG changes – Biochemical cardiac markers – Initial management

Definitions – Acute coronary syndrome Any constellation of clinical symptoms that are compatible with acute myocardial ischemia. It encompasses a spectrum from AMI  NSTEMI  UA NSTEMI – acute process of myocardial ischemia resulting in myocardial necrosis.The initial ECG does not show ST elevation

Definitions – Acute coronary syndrome UA – an acute process of myocardial ischemia that does not result in myocardial necrosis

Why be concerned re risk 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

HISTORY

History – 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 ACS High – Chest/L) arm pain as chief symptom,similar to previous angina Known Hx of CAD (including MI) Intermediate – Chest/L) arm pain as chief symptom Age>70yrs/Male/Diabetes Low – Probable ischemic symptoms in absence of any of the intermediate likelihood characteristics Recent cocaine use

History – short term risk of death or nonfatal MI in unstable angina High – Accelerating tempo of ischemic symptoms in preceding 48hrs Pain – Prolonged ongoing (>20min) rest pain Intermediate – Prior MI, peripheral or CVS/CABG/Aspirin use Pain – 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 death or nonfatal MI in unstable angina 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 EXAMINATION

Examination - diagnosing ACS High – Transient MR, hypotension,diaphoresis, pulmonary oedema Intermediate – Extracardiac vascular disease Low – Chest discomfort reproduced by palpation

Examination - short term risk of death or nonfatal MI in UA High – Pulmonary odema, most likely secondary to ischemia New or worsening MR murmur S 3 or new/worsening creps Hypotension / Bradycardia / Tachycardia Age > 75yrs Intermediate – Age >70yrs

Examination - short term risk of death or nonfatal MI in UA  Cardiogenic shock occurs in up to 5% of patients with NSTEMI and mortality rates are greater than 60%

THE ECG

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 ACS  A completely normal ECG in a patient with chest pain DOES NOT exclude the possibility of ACS % 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 nonfatal MI in unstable angina High – Angina at rest with transient ST-segment changes > 0.05mV Bundle – branch block, new or presumed new Sustained ventricular tachycardia Intermediate – T wave inversion >0.2mV Pathological Q waves Low – Normal/unchanged ECG during an episode of chest pain

ECG - short term risk of death or nonfatal 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 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 ACS High – Elevated troponins or CK-MB Intermediate – Normal Low - Normal

A- myoglobin/CK-MB isoforms after AMI B – Cardiac Troponin after AMI C - CK-MB after AMI D – Cardiac Troponin after UA

BCM - short term risk of death or nonfatal MI in unstable angina 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) Advantages - Rapid, cost- efficient accurate assays. Able to detect early reinfarction Disadvantages – Loss of specificity Low sensitivity during very early MI (6hr after sxs onset) or later after sxs onset (>36hr) and for minor myocardial damage

BCM – CK-MB isoforms Advantages – Early detection of early MI (3-6hrs after onset of sxs) Disadvantages – Specificity profile similar to that of CK-MB Current assays require special expertise (used predominately in research centers)

BCM - Myoglobin Advantages – High sensitivity Useful 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 disease Rapid return to normal Should not be used in isolation

BCM – 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 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 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 - management Assign patients with chest pain to 1 of 4 groups – 1) Noncardiac – 2) Chronic stable angina – 3) Possible ACS – 4) Definite ACS

Putting it together Most important baseline features assoc with death (Boersma et al) Age Heart rate Systolic BP ST- segment depression Signs of heart failure Elevation of cardiac markers

Putting it together 7 point risk score (Antman et al) Age (>65yrs) More than 3 coronary risk factors Prior angiographic coronary obstruction ST – segment deviation More than 2 angina events within 24hrs Use of aspirin within 7 days Elevated cardiac markers

ANY QUESTIONS ???????

Summary Risk stratification in ACS involves assessment of History Examination ECG Biochemical cardiac markers Risk stratification is used in determining management and assessing prognosis

Summary 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