Management & Risk stratification of a patient

presenting with features of ACS

Introduction• The clinical presentation of myocardial ischemia is

most often acute chest discomfort

• Goal of emergency department evaluation is to determine the cause of the chest discomfort and promptly initiate appropriate therapy

• It is essential that initial assessment and management be rapid but methodical and evidence-based

Diagnostic Evaluation• To distinguish among the following potential causes

of chest pain:– ACS– Non ischemic chest pain

• The diagnosis of acute coronary ischemia depends upon:– characteristics of the chest pain– specific associated symptoms– abnormalities on electrocardiogram (ECG), and – levels of serum markers of cardiac injury.

Criteria for Diagnosis• An ACS patient can be diagnosed as either of the following:New ST elevation at the J point in two anatomically contiguous leads

using the following diagnostic thresholds: ≥0.1 mV (1 mm) in all leads other than V2-V3, where the following

diagnostic thresholds apply: ≥0.2 mV (2 mm) in men ≥ 40 years; ≥0.25 mV (2.5 mm) in men <40 years, or ≥0.15 mV (1.5 mm) in women

New horizontal Or down-sloping ST depression ≥0.05 mV (0.5 mm) in two anatomically contiguous leads and/or T inversion

≥0.1 mV (1 mm) in two anatomically contiguous leads with prominent R wave or R/S ratio >1.

STEMI

NSTEMI/UA

Risk Stratification after acute STEMI

Early risk stratification• All patients with STEMI should undergo risk

assessment within the first four to six hours of hospitalization

• Many risk assessment models are available

• TIMI Risk score or the GRACE risk model are the preferred ones as these tools include predictors of poor outcomes identified in large databases of patients with STEMI treated with fibrinolysis

• For those treated with primary PCI, the Zwolle primary PCI risk index and the CADILLAC risk score are used

TIMI risk scoreTIMI Risk Score Predicts 30 Day Mortality After an MI

GRACE risk modelConsists of 8 independent risk factors● Age● Killip class ● Systolic blood pressure● Presence of ST segment deviation● Cardiac arrest during presentation● Serum creatinine concentration● Presence of elevated serum cardiac biomarkers● Heart rate

Point scores are assigned for each predictive factor and are added together to arrive at an estimate of the risk of in-hospital mortality.

A nomogram was published with the GRACE risk model to allow calculation of risk score

It is also available as an app

CADILLAC risk scorePatients are stratified into three risk groups that predict 30-day and one-year mortality: Low risk: (score 0 to 2) – 0.1 to

0.2% at 30 days and 0.8 to 0.9% at one year

Intermediate risk (score 3 to 5) – 1.3 to 1.9%at 30 days and 4.0 to 4.5% at one year

High risk (score ≥6) – 6.6 to 8.1% at 30 days and 12.4 to 13.2% at one year

Zwolle primary PCI index The Zwolle index generates a

risk score, on a scale of 0 to 16, that is calculated after the patient has undergone a PCI procedure

Score 0 to 3: Low risk & can be discharged

Score 4 or more: Are considered as high-risk category

LATE RISK STRATIFICATION• Late risk stratification is performed before or sometimes after

discharge (generally 3 to 7 days after the myocardial infarction and can be used to consider early discharge in patients with a low risk of complications and to help patients understand their long-term prognosis

• The main components are measurement of the left ventricular ejection fraction and stress testing

• Stress testing is used to detect possible residual ischemia in those patients who did not undergo coronary angiography or to assess the functional significance of residual coronary artery stenoses.

Left ventricular ejection fraction

• LVEF is usually measured before discharge in the absence of a specific indication; however this may be misleading, since improvement in LVEF is common in patients who are reperfused

• Multiple imaging techniques available; however echocardiography is preferred since it can also be used to assess other factors such as concurrent RV dysfunction, left atrial enlargement, mitral regurgitation, and a high wall motion score index

Stress testingObjectives: To detect residual ischemia in those patients who did not

undergo coronary angiography To assess the functional significant of residual coronary artery

stenoses To assess the exercise capacity needed for the cardiac

rehabilitation exercise prescription To identify arrythmias

• Predischarge stress testing is generally not performed in patients who have undergone PCI or CABG and have been fully revascularized

• Patients who have undergone partial revascularization or no revascularization, are candidates for predischarge testing.

• Candidates for post-MI stress testing should be properly screened

• Low level exercise testing appears to be safe if:– The patient has undergone in-hospital cardiac

rehabilitation– There have not been symptoms of HF or recurrent angina– The ECG has been stable for 48 to 72 hours prior to the

exercise test• Stress testing should not be performed in patients

with– unstable post-infarction angina, – decompensated heart failure, or – life-threatening cardiac arrhythmias

Risk Stratification after acute NSTEMI

Very high-risk patients• Individuals with any one of the following clinical

characteristics are deemed to be at such high risk that formal early risk stratification is not necessary.

• These patients typically need to proceed to urgent coronary angiography. They are patients with: – Cardiogenic shock

– Overt heart failure (HF) or severe left ventricular dysfunction

– Recurrent or persistent rest angina despite intensive medical therapy

– Hemodynamic instability due to mechanical complications (eg, acute mitral regurgitation, ventricular septal defect)

– Unstable ventricular arrhythmias

EARLY RISK STRATIFICATION TOOLS

TIMI risk score

TIMI risk index

GRACE risk model

CRUSADE long-term mortality risk score

CHADS2 score

TIMI risk score• To calculate the score, a value of 1 is assigned when

each variable was present and 0 when it was absent

GRACE Risk Score• The GRACE risk score provides the most accurate

stratification of risk both on admission and at discharge due to its good discriminative power

• Has 8 components: Age, Killip class, Systolic BP, presence of ST segment deviation, cardiac arrest during presentation, serum creatinine concentration, presence of elevated serum cardiac biomarkers & heart rate

• However, the complexity of the estimation requires the use of computer or personal digital assistant software for risk calculations

Mortality in hospital and at 6 months in low, intermediate, and high risk categories in registry populations, according to the GRACE risk score

USING THE RESULTS OF EARLY RISK STRATIFICATION

• Patients at high risk as determine by the use of the risk scores discussed above are usually referred for angiography, if it has not already been performed

• For intermediate and low-risk patients who do not undergo early angiography, noninvasive testing prior to discharge may provide information that leads to a decision to perform angiography.

LATE RISK STRATIFICATION

• It is performed three to seven days after the event

• Helps in determining long-term management and prognosis

• The main components are measurement of the left ventricular ejection fraction and, primarily in medically managed patients, stress testing to detect possible residual ischemia

Left ventricular function• In the absence of a specific indication (eg, heart failure or

suspected mechanical complication), the LVEF is usually measured before discharge

• However it can be misleading since improvement in LVEF, beginning within three days and largely complete by 14 days, is common in patients who either reperfuse spontaneously or undergo percutaneous coronary intervention (PCI).

• This is believed to reflect recovery from myocardial stunning

• Added advantage of detecting other prognostic factors like diastolic dysfunction, concurrent RV dysfunction, increased left atrial volume, mitral regurgitation, and a high wall motion score index

Stress testing• It can be used to detect residual ischemia and to assess the

exercise capacity needed for the cardiac rehabilitation exercise prescription

• In PCI/CABG patients who have been fully revascularized: Exercise testing done few weeks after discharge

• Patients who have undergone partial revascularization or no revascularization: Predischarge testing is done

• In patients with baseline ECG abnormalities, accurate ECG interpretation is not possible. In such cases, either exercise radionuclide myocardial perfusion imaging (rMPI) or exercise echocardiography can be performed.

References• http://www.uptodate.com/contents/initial-evaluation-and-

management-of-suspected-acute-coronary-syndrome-myocardial-infarction-unstable-angina-in-the-emergency-department

• http://www.uptodate.com/contents/risk-stratification-after-non-st-elevation-acute-coronary-syndrome

• http://www.uptodate.com/contents/risk-stratification-after-acute-st-elevation-myocardial-infarction