Risk Stratification In Patients With Chronic Myocardial Ischemia

1. Risk Stratification In Patients With Chronic Myocardial Ischemia

2. Available methods for risk stratification in CAD patients Clinical parameters ECG Chest x-ray Noninvasive testing Resting LV function Exercise test Stress imaging Coronary angiography The recommendations are taken from the ACC/AHA 2002 Guideline Update for the Management of Patients with Chronic Stable Angina. Five clinical parameters have been identified that independently predict severe CAD: age, typical angina, diabetes, gender, and prior MI. Patients with resting ECG abnormalities are at greater risk than those with normal ECGs. Presence of cardiomegaly, an LV aneurysm, or pulmonary venous congestion on the chest x-ray also identifies patients at higher risk. Measurement of LV systolic function may be useful in the chronic stable angina patient who has a history of MI, signs of heart failure, a systolic murmur, or ventricular arrhythmias. Exercise testing should be considered during initial evaluation, unless it is decided that the extra information obtained would not be worth the extra cost. Stress imaging should be reserved for patients with resting ECG abnormalities and severe coronary calcification, patients who are unable to exercise, and as a second test for patients with an intermediate- or high-risk Duke treadmill score. Extent and severity of coronary disease as assessed by angiography are important predictors of clinical outcome. However, coronary angiography cannot identify plaques that are likely to rupture. The recommendations are taken from the ACC/AHA 2002 Guideline Update for the Management of Patients with Chronic Stable Angina. Five clinical parameters have been identified that independently predict severe CAD: age, typical angina, diabetes, gender, and prior MI. Patients with resting ECG abnormalities are at greater risk than those with normal ECGs. Presence of cardiomegaly, an LV aneurysm, or pulmonary venous congestion on the chest x-ray also identifies patients at higher risk. Measurement of LV systolic function may be useful in the chronic stable angina patient who has a history of MI, signs of heart failure, a systolic murmur, or ventricular arrhythmias. Exercise testing should be considered during initial evaluation, unless it is decided that the extra information obtained would not be worth the extra cost. Stress imaging should be reserved for patients with resting ECG abnormalities and severe coronary calcification, patients who are unable to exercise, and as a second test for patients with an intermediate- or high-risk Duke treadmill score. Extent and severity of coronary disease as assessed by angiography are important predictors of clinical outcome. However, coronary angiography cannot identify plaques that are likely to rupture.

3. High-risk criteria Severe resting LV dysfunction (LVEF <35%) High-risk treadmill score (=-11) Severe exercise LV dysfunction (LVEF <35%) Stress-induced large perfusion defect (esp anterior) Multiple, moderate-sized perfusion defects Large, fixed perfusion defect with LV dilation or increased lung uptake (thallium-201) Stress-induced moderate perfusion defect with LV dilation or increased lung uptake (thallium-201) Echocardiographic wall motion abnormality (>2 segments) at low dobutamine dose (=10 mg/kg per min) or low HR (<102 bpm) Stress echocardiographic evidence of extensive ischemia High-risk patients are generally referred for coronary angiography. These criteria are based on studies in symptomatic patients, but are probably also applicable to asymptomatic patients. Asymptomatic patients with high-risk characteristics would be considered for coronary angiography (Class IIa recommendation, level of evidence C).High-risk patients are generally referred for coronary angiography. These criteria are based on studies in symptomatic patients, but are probably also applicable to asymptomatic patients. Asymptomatic patients with high-risk characteristics would be considered for coronary angiography (Class IIa recommendation, level of evidence C).

4. Intermediate-risk criteria Mild/moderate resting LV dysfunction (LVEF 35%-49%) Intermediate-risk treadmill score (-11 < score < 5) Stress-induced moderate perfusion defect without LV dilation or increased lung intake (thallium-201) Limited stress echocardiographic ischemia with a wall motion abnormality only at higher doses of dobutamine involving =2 segments Test findings that identify intermediate-risk patients are summarized. Test findings that identify intermediate-risk patients are summarized.

5. Low-risk criteria Low-risk treadmill score (=5) Normal or small myocardial perfusion defect at rest or with stress Normal stress echocardiographic wall motion or no change of limited resting wall motion abnormalities during stress Test findings that identify low-risk patients are summarized. Test findings that identify low-risk patients are summarized.

6. Comparison of 3 different risk scores The TIMI, PURSUIT (Platelet Glycoprotein IIb/IIIa in Unstable Angina: Receptor Suppression Using Integrilin), and GRACE (Global Registry of Acute Coronary Events) risk scores were developed to assess short-term prognosis in patients with acute coronary syndromes. Subsequently, they were shown to help risk stratify patients up to 1 year post-MI. As shown, all three scores demonstrated good predictive accuracy for death or MI at 1 year.The TIMI, PURSUIT (Platelet Glycoprotein IIb/IIIa in Unstable Angina: Receptor Suppression Using Integrilin), and GRACE (Global Registry of Acute Coronary Events) risk scores were developed to assess short-term prognosis in patients with acute coronary syndromes. Subsequently, they were shown to help risk stratify patients up to 1 year post-MI. As shown, all three scores demonstrated good predictive accuracy for death or MI at 1 year.

7. Summary Chronic IHD continues to impose a high socioeconomic burden Mechanistic understanding has undergone a paradigm shift Traditional focus: Determinants of myocardial O2 supply/demand Contemporary focus: Changes in Na+ and Ca2+ currents during ischemia Contemporary management: Aggressive treatment of multiple risk factors Multifactorial treatment of symptoms Renewed interest in the role of optimal medical therapy vs PCI While chronic ischemic heart disease continues to pose a major clinical challenge, advances have been made in understanding both the underlying pathophysiology and the clinical management of this disease. Intriguing data that late Na(+) current inhibition may have antiarrhythmic as well as anti-ischemic effects suggest that further advances in optimal medical therapy may be possible. Recent clinical trials have generated considerable debate over the relative roles of medical therapy and coronary revascularization. This debate, though still unresolved, illustrates the important fact that treatment options today are broader than ever.While chronic ischemic heart disease continues to pose a major clinical challenge, advances have been made in understanding both the underlying pathophysiology and the clinical management of this disease. Intriguing data that late Na(+) current inhibition may have antiarrhythmic as well as anti-ischemic effects suggest that further advances in optimal medical therapy may be possible. Recent clinical trials have generated considerable debate over the relative roles of medical therapy and coronary revascularization. This debate, though still unresolved, illustrates the important fact that treatment options today are broader than ever.