Diagnosis and Management of Coronary Artery Disease

The most common cause of death in older adults is coronary artery disease (CAD). Coronary atherosclerosis is very common in older adults, with autopsy studies demonstrating a prevalence of at least 70% in persons older than 70 years. The prevalence of CAD is similar in older women and men. In one study, clinical CAD was present in 502 of 1160 men (43%), mean age 80 years, and in 1019 of 2464 women (41%), mean age 81 years. At 46-month follow-up, the incidence of new coronary events (myocardial infarction, sudden cardiac death) was 46% in the older men and 44% in the older women.

CAD is diagnosed in older adults if they have coronary angiographic evidence of significant CAD, documented myocardial infarction (MI), typical history of angina pectoris with myocardial ischemia diagnosed by stress testing, or sudden cardiac death. The incidence of sudden cardiac death as the first clinical manifestation of CAD increases with age.

Clinical Manifestations

Dyspnea on exertion is a more common clinical manifestation of CAD in older adults than the typical chest pain of angina pectoris. The dyspnea is usually exertional and is related to a transient rise in left ventricular (LV) end-diastolic pressure caused by ischemia superimposed on reduced LV compliance. Because older adults are more limited in their activities, angina pectoris is less often associated with exertion. Older adults with angina pectoris are less likely to have substernal chest pain, and they describe their anginal pain as less severe and of shorter duration than younger persons. Angina pectoris in older adults may occur as a burning postprandial epigastric pain or as pain in the back or shoulders. Acute pulmonary edema unassociated with an acute MI may be a clinical manifestation of unstable angina pectoris due to extensive CAD in older adults.

Myocardial ischemia, appearing as shoulder or back pain in older adults , may be misdiagnosed as degenerative joint disease. Myocardial ischemia, appearing as epigastric pain, may be misdiagnosed as peptic ulcer disease. Nocturnal or postprandial epigastric discomfort that is burning in quality may be misdiagnosed as hiatus hernia or esophageal reflux instead of myocardial ischemia because of CAD. The presence of comorbid conditions in older adults may also lead to misdiagnosis of symptoms as a result of myocardial ischemia.

Older adults with CAD may have silent or asymptomatic myocardial ischemia. In a prospective study of older adults with CAD, 133 of 195 men (68%), mean age 80 years, and 256 of 771 women (33%), mean age 81 years, had silent myocardial ischemia detected by 24-hour ambulatory electrocardiograms (ECGs). At 45-month follow-up, the incidence of new coronary events in older men with CAD was 90% in those with silent myocardial ischemia versus 44% in older men without silent ischemia. At 47-month follow-up, the incidence of new coronary events in older women with CAD was 88% in those with silent ischemia versus 43% in older women without silent ischemia.

The reason for the frequent absence of chest pain in older patients with CAD is unclear.

Recognized and Unrecognized Myocardial Infarction

Pathy reported that in 387 older patients with acute MI, 19% had chest pain, 56% had dyspnea or neurologic or gastrointestinal symptoms, 8% had sudden death, and 17% had other symptoms. Another study showed that in 110 older patients with acute MI, 21% had no symptoms, 22% had chest pain, 35% had dyspnea, 18% had neurologic symptoms, and 4% had gastrointestinal symptoms ( Box 40-1 ). Other studies have also shown a high prevalence of dyspnea and neurologic symptoms in older patients with acute MI. In these studies, dyspnea was present in 22% of 87 patients, in 42% of 777 patients, and in 57% of 96 patients. Neurologic symptoms were present in 16% of 87 patients, 30% of 777 patients, and 34% of 96 patients.

Box 40-1

Modified from Aronow WS: Prevalence of presenting symptoms of recognized acute myocardial infarction and of unrecognized healed myocardial infarction in elderly patients. Am J Cardiol 60:1182, 1987.

Presenting Symptoms in 110 Older Patients With Acute Myocardial Infarction

Dyspnea was present in 35% of patients.
Chest pain was present in 22% of patients.
Neurologic symptoms were present in 18% of patients.
Gastrointestinal symptoms were present in 4% of patients.
No symptoms were present in 21% of patients.

As with myocardial ischemia, some patients with acute MI may be completely asymptomatic or the symptoms may be so vague that they are unrecognized by the patient or physician as an acute MI. Studies have reported that 21% to 68% of MIs in older patients are unrecognized or silent. These studies also found that the incidence of new coronary events, including recurrent myocardial infarction, ventricular fibrillation, and sudden death in patients with unrecognized MI is similar to or higher than in patients with recognized MI.

Older patients with acute MI have a higher prevalence of non–ST-segment elevation MI (NSTEMI) with absence of pathologic Q waves than ST-segment elevation MI (STEMI) with pathologic Q -waves. Of 91 consecutive patients with acute MI aged 70 years and older, mean age 78 years, 61 (75%) had NSTEMI. Of 4,017,367 patients aged 65 years and older with acute MI during 2001to 2010, 64.3% had NSTEMI. During this period, STEMI decreased 16.4% in patients with acute MI aged 65 to 79 years and by 19% in patients with acute MI aged 80 years and older.

Diagnostic Techniques

Resting Electrocardiography

In addition to diagnosing recent or prior MI, the resting ECG may show ischemic ST-segment depression, arrhythmias, conduction defects, and LV hypertrophy related to subsequent coronary events. At 37-month mean follow-up, older patients with ischemic ST-segment depression 1 mm or greater on the resting ECG were 3.1 times more likely to develop new coronary events than were older patients with no significant ST-segment depression. Older patients with ischemic ST-segment depression of 0.5 to 0.9 mm on the resting ECG were 1.9 times more likely to develop new coronary events during 37-month follow-up than older patients with no significant ST-segment depression. At 45-month mean follow-up, pacemaker rhythm, atrial fibrillation, premature ventricular complexes, left bundle branch block, intraventricular conduction defect, and type II second-degree atrioventricular block were associated with a higher incidence of new coronary events in older patients. Numerous studies have also demonstrated that older patients with LV hypertrophy on the ECG have an increased incidence of new coronary events.

Many studies have found that complex ventricular arrhythmias in older adults with CAD are associated with an increased incidence of new coronary events, including sudden cardiac death. The incidence of new coronary events is especially increased in older adults with complex ventricular arrhythmias and abnormal LV ejection fraction (LVEF) or LV hypertrophy. At 45-month follow-up of 395 men with CAD, mean age 80 years, complex ventricular arrhythmias detected by 24-hour ambulatory ECGs significantly increased the incidence of new coronary events by 2.4-fold. At 47-month follow-up of 771 women with CAD, mean age 81 years, complex ventricular arrhythmias detected by 24-hour ambulatory ECGs significantly increased the incidence of new coronary events by 2.5-fold. Over an 8-year follow-up of 2192 ambulatory volunteers aged 70 to 79 years without CAD, major baseline ECG abnormalities (Q waves, bundle branch block, atrial fibrillation or flutter, or major ST-T wave changes) were associated with a 50% increased risk of coronary events independent of conventional risk factors. Minor ST-T changes were associated with a 35% increased risk of coronary events independent of conventional risk factors.

Stress Testing

Exercise Stress Testing

Hlatky and colleagues found the exercise ECG to have a sensitivity of 84% and specificity of 70% for the diagnosis of CAD in persons older than 60 years. Newman and Phillips found a sensitivity of 85%, specificity of 56%, and positive predictive value of 86% for the exercise ECG in diagnosing CAD. The increased sensitivity of the exercise ECG with increasing age found in these two treadmill exercise studies was probably due to the increased prevalence and severity of CAD in older adults.

Exercise stress testing also has prognostic value in older patients with CAD. Deckers and associates demonstrated that the 1-year mortality was 4% for 48 patients 65 years of age or older who were able to do an exercise stress test after acute MI and 37% for the 63 older patients unable to do the exercise stress test after acute MI.

Exercise stress testing using thallium perfusion scintigraphy, radionuclide ventriculography, and echocardiography is also useful for the diagnosis and prognosis of CAD. Iskandrian and coworkers showed that exercise thallium-201 imaging can be used for risk stratification of older patients with CAD. The risk for cardiac death or nonfatal MI at 25-month follow-up in 449 patients 60 years of age or older was less than 1% in patients with normal images, 5% in patients with a single-vessel thallium-201 abnormality, and 13% in patients with multivessel thallium-201 abnormality.

Pharmacologic Stress Testing

Intravenous (IV) dipyridamole thallium imaging may be used to determine the presence of CAD in older patients who are unable to undergo treadmill or bicycle exercise stress testing. In patients 70 years of age or older, the sensitivity of IV dipyridamolethallium imaging for diagnosing significant CAD was 86% and the specificity was 75%. In 120 patients older than 70 years, adenosine echocardiography had a 66% sensitivity and 90% specificity in diagnosing CAD. An abnormal adenosine echocardiogram predicted a threefold risk of future coronary events, independent of coronary risk factors. In 120 patients older than 70 years, dobutamine echocardiography had a 87% sensitivity and 84% specificity in diagnosing CAD. An abnormal dobutamine echocardiogram predicted a 7.3-fold risk of future coronary events. In 101 patients older than 70 years, the sensitivity and specificity of dipyridamole thallium imaging for CAD were 86% and 75%, respectively, compared with 83% and 70%, respectively, in younger patients. Dobutamine stress echocardiography predicted at 3-year follow-up in 227 octogenarians a 2.7-fold increase in all-cause mortality and a 3.2-fold increase in major cardiovascular events.

Electrocardiography

Ambulatory Electrocardiography

Ambulatory electrocardiography performed for 24 hours is also useful for detecting myocardial ischemia in older adults with suspected CAD who cannot perform treadmill or bicycle exercise stress testing because of advanced age, intermittent claudication, musculoskeletal disorders, heart failure, or pulmonary disease. Ischemic ST-segment changes demonstrated on 24-hour ambulatory ECGs correlate with transient abnormalities in myocardial perfusion and LV systolic dysfunction. The changes may be associated with symptoms, or symptoms may be completely absent, which is referred to as silent myocardial ischemia. Silent myocardial ischemia is predictive of future coronary events, including cardiovascular mortality in older adults with CAD. The incidence of new coronary events is especially increased in older adults with silent myocardial ischemia plus complex ventricular arrhythmias, abnormal LVEF, or echocardiographic LV hypertrophy.

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