RISK STRATIFICATION for Acute Coronary Syndrome in the Emergency Department Sohil Pothiawala FAMS (EM), MRCSEd (A&E), M.Med (EM), MBBS Consultant Dept. of Emergency Medicine Singapore General Hospital
Overview Definition of Acute coronary syndrome (ACS) Why risk stratification? Factors incorporated in risk stratification History Examination Diagnostic studies eg. ECG, Biochemical cardiac markers, other tests Scoring systems
Definition Acute coronary syndrome Constellation of clinical symptoms that are compatible with acute myocardial ischemia Encompasses a spectrum from AMI NSTEMI UA
Why risk stratification Determine the likelihood of symptoms representing ACS v/s other differential diagnosis Select appropriate Therapy (PCI v/s medical) Select site of care (ICU v/s telemetry) Determine the risk of adverse outcomes (eg death, MI, stroke, CHF, recurrent ischemia, arrhythmias) Risk stratification should be ongoing at admission, 6-8 hrs, 24hrs, discharge
History 5 most important factors that relate to the likelihood of ischemia due to CAD Nature of the anginal symptoms/equivalents Prior Hx of CAD Sex Age Number of traditional risk factors present
BEWARE women, diabetics, renal pts and elderly Description of chest pain alone cannot be used to rule out CAD Traditional risk factors are only weakly predictive of likelihood of acute ischemia, but help predict poor outcomes
Atypical Presentations of ACS Most frequent angina equivalents - SOB>Weakness>Unusual Fatigue>Sweats>Dizziness Associated symptoms most predictive of MI: ED observed sweating>vomiting>radiation to both arms>radiation to R arm Radiation to the L arm did not increase the likelihood of MI in recent study in Resuscitation, 2010 7% of pts with ACS will have pleuritic chest pain 7% of pts have their pain partially or fully reproduced on chest wall palpation Conclusion: Atypical is the new Typical ie. Atypical presentations of ACS are common
Value of Physical Examination Exclude other diagnoses pulse deficit, new aortic regurg murmur and neuro deficit in aortic dissection unilateral decreased air entry and JVD in tension pneumothorax friction rub, muffled heart sound and JVD in pericarditis with tamponade Prognostication look for signs of CCF (JVD, S3, crackles and peripheral edema) has worse Px aortic stenosis murmur (critical AS with ischemia carries very poor prognosis) new mitral regurg murmur (ominous sign of papillary muscle rupture)
ECG A completely normal ECG in a patient with chest pain DOES NOT exclude the possibility of ACS 1-6% proven to have AMI, 4% unstable angina Single ECG for AMI sensitivity of 60%, specificity 90% Represents single point in time needs to be read in context Trend towards increased mortality when ischemia not initially diagnosed on ECG Serial ECGs or ECG adjuncts more sensitive than the presenting ECG alone
Biochemical cardiac markers Useful in both the diagnosis of myocardial necrosis (STEMI/NSTEMI) as well as treatment implications Prognostically, there is a quantitative relationship between the magnitude of elevation of marker levels and the risk of an adverse event
Cardiac Biomarkers 2 sets of Troponins (6-8hrs apart) are indicated for all pts (except those that have isolated CP >12hrs prior to ED visit who only need 1 Troponin) High-sensitive Troponins turn positive sooner than older Troponins - 1hr and 3hr post CP high-sensitive Troponin has a near 100% sensitivity to rule out MI in low risk patients However, they are less specific than the traditional Troponins (N Eng J Med, Aug 2009) Differentials of elevated Troponin: PE, myocarditis, sepsis, post-cardioversion, CHF Troponin levels reflect increased risk of death/mi regardless of renal dysfunction (N Engl J Med 2002; 346:2047-2052) When to use CK-MB? CK-MB returns to baseline in 2-4days v/s Troponin in 1 wk. So if pt presents with CP 5 days after being discharged with MI, the CK-MB is helpful to determine whether the Troponin rise is from the MI that occurred 5 days ago v/s pt has reinfarcted today
IMAGING MODALITIES Multi-detector CT for coronary calcification Coronary CT angiography Cardiac MRI Diagnostic Utility of Recent Cardiac Testing for ED Patients with Chest Pain up to 2/3 of AMIs caused by stenotic plaques <50% occlusive, so tests based on stenosis can be misleading treadmill stress test has only 68% sensitivity and 77% specificity for single vessel disease a recent negative angiogram does not rule out ACS in the ED patient
Risk Scores IS C H A E M IA TIMI (Thrombolysis in Myocardial Infarction) PURSUIT (Platelet glycoprotein IIb/IIIa in Unstable angina: Receptor Suppression Using Integrilin Therapy) GRACE (Global Registry of Acute Cardiac Events) B L E E D I N G HEART CRUSADE (Can Rapid risk stratification of Unstable angina patients supress ADverse outcomes with Early implementation of the ACC/AHA guidelines) ACUITY (Acute catheterization and Urgent Intervention Triage Strategy)
Historical Age 65 TIMI Risk Score increased mortality with increasing score ~40% all cause mortality at 14 days for patients requiring urgent revascularisation 1 point 3 or more CHD risk factors 1 point Known CHD (stenosis 50%) Use of aspirin in previous 7 days 1 point 1 point Presentation At least 2 angina events in past 24 hrs 1 point ST deviation 0.5mm 1 point cardiac markers (TnT or CK-MB) 1 point Risk Score Total (0-7) Antman EM, et al. The TIMI risk score for unstable angina/non-st elevation MI. JAMA 2000;284:835-842
Why use the TIMI Risk Score? - Means of integrating all clinical factors and markers to be a comprehensive risk stratification tool - Developed on basis on endpoints of death, MI or severe recurrent ischemia v/s mortality - Well validated in clinical trials - Simple tool to predict benefit of therapies
PURSUIT Risk factors for AMI Age (decade) Gender Highest Canadian Cardiovascular Society angina classification in previous 6 weeks Heart rate Systolic blood pressure Signs of heart failure (eg, rales) ST depression on presenting ECG Score range 0-25 Predicts 30-day risk Boersma E, et al. for the PURSUIT investigators. Circulation 2000;101:2557-67
GRACE Score for in-hospital mortality Killip heart failure class Systolic blood pressure Heart rate Age Creatinine level Cardiac arrest at admission ST-segment deviation Elevated cardiac enzyme levels Granger CB, et al. Predictors of hospital mortality in the GRACE. Arch Intern Med. 2003; 163:2345-53
HEART score History ECG Age Risk Factors Troponin Score is the sum of these 5 factors Score 0-3: discharge (2.5% risk of Adverse Event) 4-6: observation (20% risk) >7: invasive strategies (72% risk) Six AJ, et al. Chest pain in the emergency room:value of the HEART score. Neth Heart J. 2008;16(6):191-196
WHICH MODEL IS MOST APPROPRIATE?? ACC/AHA GUIDELINES: Risk stratification models useful in decision making with regard to treatment options TIMI vs GRACE vs PURSUIT vs HEART PURSUIT & GRACE risk scores allow better discrimination of in hospital and 1 year mortality in patients compared to TIMI. (Andrew et al, Risk scores for risk stratification in ACS )
Summary ED evaluation is the key Risk stratification in ACS involves assessment of History Examination ECG Biochemical cardiac markers Risk Stratification Scores Risk stratification will determine the need for appropriate management and assessing prognosis
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