Diagnosis

Ischemic Heart Disease - Diagnosis

• Important aspects of the clinical history include the nature or quality of the chest pain, precipitating factors, duration, pain radiation, and the response to nitroglycerin or rest. There appears to be little relationship between the historical features of angina and the severity or extent of coronary artery vessel involvement. Ischemic chest pain may resemble pain arising from a variety of noncardiac sources, and the diferential diagnosis of anginal pain from other etiologies may be difficult based on history alone.
• The patient should be asked about existing personal risk factors for coronary heart disease (CHD) including smoking, hypertension, and diabetes mellitus.
• A detailed family history should be obtained that includes information about premature CHD, hypertension, familial lipid disorders, and diabetes mellitus.
• There are few signs on physical examination to indicate the presence of CAD. Findings on the cardiac examination may include abnormal precordial systolic bulge, decreased intensity of S1, paradoxical splitting of S2, S3, S4, apical systolic murmur, and diastolic murmur. Elevated heart rate or blood pressure can yield an increased DP and may be associated with angina. Noncardiac physical findings suggesting significant cardiovascular disease include abdominal aortic aneurysms or peripheral vascular disease.
• Recommended laboratory tests include hemoglobin (to ensure adequate oxygen-carrying capacity), fasting glucose (to exclude diabetes), and fasting lipoprotein panel. Important risk factors in some patients may include C-reactive protein, homocysteine level, evidence of Chlamydia infection, and elevations in lipoprotein (a), fibrinogen, and plasminogen activator inhibitor. Cardiac enzymes should all be normal in stable angina. Troponin T or I, myoglobin, and CK-MB may be elevated in unstable angina.
• The resting ECG is normal in about one-half of patients with angina who are not experienceing an acute attack. Typical ST-T-wave changes include depression, T-wave inversion, and ST-segment elevation. Variant angina is associated with ST-segment elevation, whereas silent ischemia may produce elevation or depression. Significant ischemia is associated sith ST-segment depression of greater than 2mm, exertional hypotension, and reduced exercise tolerance.
• Exercise tolerance (stress) testing (ETT) is recommended for patients with an intermediate probability of CAD. Results correlate well with the likelihood of progressing to angina, occurrence of AMI, and cardiovascularevents and mortality. Thallium (201Tl) myocardial perfusion scintigraphy may be used in conjunction with ETT to detect reversible and irreversible defects in blood flow to the myocardium.
• Radionuclide angiocardiography is used to measure ejection fraction (EF). regional ventricular performance, cardiac output, ventricular volumes, valvular regurgitation, asynchrony or wall motion abnormalities, and intracardiac shunts.
• Ultrarapid computed tomography may minimize artifact from heart motion during contraction and relaxation and provides a semiquantitative assessment of calcium content in coronary arteries.
• Echocardiogarphy is useful if the history or physical findings suggest valvular pericardial disease or ventricular dysfunction. In patients unable to exercise, pharmacologic stress echocardiography (eg. Dobutamine, Dipyridamole, or Adenosine) may identify abnormalities that would occur during stress.
• Cardiac catheterization and coronary angiography are used in patients with suspected CAD to document the presence and severity of disease as well as for prognostic purposes. Interventional catheterization is used for thrombolytic therapy in patients with AMI and for managing patients with significant CAD to relieve obstruction through percutaneous transluminal coronary angioplasty (PTCA), atherectomy, laser treatment, or stent placement.