Health Articles

Necrosis of myocardial tissue resulting from obstruction of a coronary artery.
In the USA, most patients hospitalized with acute myocardial infarction are > 65 yr of age. The elderly are less likely to have precordial pain and more likely to have dyspnea, fatigue, weakness, orCNS symptoms such as confusion and dizziness. The different symptomatology may reflect the greater likelihood that an older person has preexisting cerebrovascular disease or heart failure.
The incidence of infarct complications, including heart failure, pulmonary edema, ventricular rupture, and death, is significantly higher in older palients. Again, these changes may result from preexisting left ventricular dysfunclion and possibly from lower contractile reserve in noninlareted regions related to diminished β-agonist responsiveness. Older patients are also more likely to have smaller and non-Q-wavc infarcts than are younger persons. This may be because the elderly are more likely to have hypotension and superimposed illnesses, such as pneumonia or anemia, which may induce a small, non-Q-wave infarction in the absence of associated coronary thrombus. Important topographic changes—regional dilation and thinning in (he infarcted area and compensatory hypertrophy in noninfarcted lissue—that occur af-ier Q-wave infarction are also related to advancing age.
Treatment
Because of a high complication rale, elderly persons benefit from close monitoring in a coronary care unit.
Early thrombolysis (within 6 h of a transmural infarction) decreases mortality and improves left ventricular function. The addition of aspirin 160 mg/day provides more benefit than that achieved with thrombolysis alone. However, thrombolytic therapy is not used as often in older patients with acute infarctions. This may be related in part to the increased likelihood of coexisting illnesses, delayed presentation, and atypical symptoms and ECG changes. Although the elderly are at increased risk for intracerebral hemorrhage, the risk may be attenuated if the dose of thrombolytic agent is weight-adjusted. When assessing the benefit-to-risk ratio, the physician should remember that the benefit of thrombolytic therapy is increased in those who are treated early and in Ihose who have extensive anterior infarctions.
Drug therapy is otherwise the same as that used in younger patients. However, because the elderly have a markedly heterogeneous response, with no strict age-related rules, therapy must be individualized. Anticoagulants arc given cautiously for two major reasons: (1) heparin is associated with an increased risk of bleeding in older women, and (2) the hazards of chronic warfarin therapy are compounded by the increased risk of falls. Aspirin is approved for prevention of reinfarction after myocardial infarction. Although studies have focused on middle-aged populations, it is reasonable and prudent lo give aspirin to the elderly as well. As in younger palients, β-blockers may be used for their secondary prevention effects (see above). Such therapy is particularly beneficial for those who are at increased risk for recurrent myocardial infarction.
Medically supervised rehabilitation after myocardial infarction results in improved conditioning similar to lhat observed in younger patients. Target heart rates arc best assessed on a Bruce treadmill test performed 3 to 6 wk after the infarction. If no evidence of exercise-induced ischemia, arrhythmia, or deterioration of left ventricular function exists, an exercise program sufficient to raise the heart rate to 70% of the maximum achieved heart rate can then be recommended (see Ch. 31). Sexual activity can usually be resumed 8 to 14 wk after myocardial infarction (see Heart Disease under EFFECTS OF MFIMCAL PROBLEMS ON SHXUALITY in Ch. 68).

If pharmacotherapy fails lo control symptoms, or if noninvasive studies (eg, the treadmill test) or the clinical selling (eg, recurrent ischemia in the postinfarction period) indicates that the pa-lienl is at high risk despile medical iherapy, cardiac catheterization should be considered to evaluate the suitability of angioplasty or coronary arlcry bypass surgery. The risks of cardiac catheterization, including cerebral and peripheral embolizalion, renal failure, and dealh, are higher in the elderly. This increased risk may be because older palients are more likely to have preexisting coronary and peripheral vascular disease, renal insufficiency, and lefl ventricular dysfunction.
Some reports indicate that angioplasty is associated with a lower success rate and an increased rate of acute complications in the elderly. However, more recent studies indicate that the success rate (83%) is comparable to that in younger patienis (86%) and thai the complication rate (9%) is only slightly higher than that in younger patients (6%).
If a patient’s coronary artery anatomy is not suitable for angioplasty, bypass surgery should be considered. Although the morlality rate may be two lo (hree times higher in older than in younger persons, this is primarily because the elderly are more likely to have hypertension, impaired ventricular function, and extensive coronary artery disease. The overall mortality rate of 5% to 6% in the elderly is low enough for surgery to be recommended if indicated. Although morbidity and hospital-izalion time and costs are greater in the elderly, the risk of complications is declining, in addition, the Iong-Ierm pain relief and survival rates of bypass surgery compare favorably with those of drug therapy.

A clinical syndrome due lo myocardial ischemia characterized by episodes of precordial discomfon and pressure, typically precipitated by exertion and relieved by rest or sublingual nitroglycerin.
Angina pectoris is a clinical manifestation of coronary artery disease. The discomfort of angina, which is highly variable, is most commonly felt beneath the sternum. It may be a vague, barely troublesome ache, or il may rapidly become a severe, intense, precordial crushing sensation. Some patients do nol perceive the discomfort as pain.
Angina is usually triggered by physical activity and typically persists for no more than a few minutes, subsiding with rest. Angina is worsened when exertion follows a meal. It is also exaggerated in cold weather. Walking into the wind or first contact with cold air on leaving a warm room may also precipitate an attack. Angina may occur at night (nocturnal angina), which may be ;i sign of recurrent left ventricular failure, ;tn equivalent of nocturnal dyspnea.
Attacks may vary in frequency from several a day lo occasional episodes separated by symptom-free intervals of weeks or months. They may increase in frequency (crescendo angina) to a fatal outcome or may gradually decrease or disappear if an adequate collateral circulation develops, if the ischemic area becomes infarcted, or if heart failure supervenes and limits activity.
Any change in the pattern of symptoms—increased intensity of attacks, decreased threshold of stimulus, longer duration, or occurrence when the patient is sedentary or awakening from sleep—should be viewed as serious. Such changes are termed unstable angina, which may be prodromal to acute myocardial infarction.
Treatment
The treatment of elderly persons wilh angina should begin with an attempt to identify other superimposed and treatable illnesses that may increase myocardial oxygen demand and decrease its supply, such as anemia, infection, hyperthyroidism, and arrhythmias. If any of these conditions are present and treated, the angina may possibly be eliminated.
Pharmacotherapy: The primary drug options are the same for elderly as for younger patients: nitrates, β-blockcrs, and calcium antagonists. Age-associated changes in pharmacokinetics and pharmacodynamics (eg, decreases in serum albumin and lean body mass and increases in cii-acid glycoproteins and body fat) may influence the choice and dose of these drugs. Aging is also associated with a change in the cardiovascular response to certain medications including β-agonisls and digitalis. Older persons are also more likely to be laking other medications that may alter the pharmacokinetics of cardiovascular agents.
Nitrates act primarily by lowering preload through venous dilation, which decreases venous return and hence ventricular cavity size, and to a lesser extern by reducing aflerload through arteriolar dilation. They may also produce coronary vasodilation. Nitroglycerin given sqb-lingually 0.3 to 0.6 nig or as a lingual aerosol spray 0.4 mg provides relief during an acute ischemic episode and is useful for prophylaxis. Unforlunately. the anli-ischemie effect of both oral (20 to 40 mg qid) and topical (5 )o 20 mg/24 h) nitrate preparations is significantly attenuated if the drug is given continuously. This can be ;ivoided by intermittent dosing. Removing Ihc transdermal patch overnight or using oral preparations bid or tid may prevent Ihc development of nitrate tolerance. However, this may leave the patient insufficiently protected between doses.
Preexisting diminished intravascular volume, impaired venous valves, and a diminished barorcceptor reflex make older patients more susceptible (o the hypotensive effecls of nitrates. Thus, it is important lo begin with a low dose, increase the dose slowly, and instruct palients to lie down when they first take any nitrate preparation.
P-Blockers work primarily by reducing myocardial oxygen demand; they decrease heart rate, myocardial contractility, and blood pressure. Secondarily, they increase myocardial oxygen supply through the reduction in hear! rate (since most of the coronary flow occurs during diastole). In addition, propranolol has been shown lo produce a right-ward shift of the oxyhemoglobin dissociation curve, thus increasing release of oxygen to ischemic tissues.
The choice of β-blocker should be based on the drug’s associated properties. Low doses of relatively cardioseleclive drugs (atenolol 50 mg/day or metoprolol 100 mg/day) may be used when blockade of p2-receptors is undesirable. However, the selectivity is only relative because blockade of P2-rcceptors occurs at moderate to high doses. Hy-drophilic β-blockers (atenolol 50 to 200 mg/day or nadolol 40 to 80 mg/day) should be considered when treating patients with hepalic disease or when CNS side effects need to be minimized. Lipophilic β-blockers (propranolol 80 to 240 mg/day, metoprolol 50 to 100 mg bid, or timolol 10 to 20 mg bid) may be preferable in patients with coexisting renal disease.
Secondary prevention is an important additional benefit of some β-blockers. Studies have shown that timolol (20 mgAlay), propranolol UfiO to 240 mg/day), and metoprolol (100 to 200 mg/day) decrease the risk of subsequent infarction and death when given after myocardial infarction.
Because of pharmacodynamic and pharmacokinetic changes (described in Ch. 21), the β-blocking properties of these drugs are diminished in the elderly. The age-related reduction in cardiovascular responsiveness to β-agonist stimulation results in less reliance on catecholamines and more dependence on the Frank-Starling mechanism to increase cardiac work during times of stress (see Chs, 33 and 41). This suggests that β-blockers as anti-ischemic agents may be less effective in elderly than in younger patients.
Preexisting disease, such as bronchospaslic pulmonary disease, claudication, insulin-dependent diabetes mellitus, impaired ventricular function, and conduction system disease, may render the elderly more sensitive to the side effects of β-blockers. Prolonged therapy may result in tip-regulation of cardiac β-receptors and hence produce an increased sensitivity to endogenous catecholamines if β-blockers are abruptly withdrawn. Thus, ^-blockers should be withdrawn slowly, if possible, when therapy is discontinued in angina patients.
Calcium antagonists are useful for treating stable and unstable angina. This group of drugs includes nifedipine 30 lo 120 mg/day. dil-liazem 90 to 360 mg/day, verapamil 120 to 480 mg/day, and the newer dihydropyridines, amlodipinc 5 to 10 mg/day and felodipine 5 to 10 mg/day.
Calcium antagonists act primarily by decreasing coronary and peripheral vascular resistance, although verapamil (and to a considerably less extent, dilliazcm) has negative inotropic and chronotropic effects. These agents exert an anti-ischemic effect (I) by decreasing coronary artery resislancc and preventing spasm, which increases myocardial oxygen supply, and (2) by inducing peripheral vasodilation, which decreases myocardial oxygen demand. They also have antiplatelet properties and an antihypertensive cffecl. which makes them useful in palients wilh coexisting hyperlension.
Because calcium antagonists have a peripheral vasodilating effect, they should be given cautiously to elderly palients. Hypotension can occur with peripheral vasodilation, especially in patients who are volume depleted. A sympalhctic reflex-induced increase in cardiac work may also occur, which can be prevented by the concomitant administration of a relatively small dose of β-blocker. Some calcium antagonists also have negative inotropic, chronotropic, and dromolropic effects, which affect primarily persons with preexisting impaired ventricular function or conduction system disease or those taking fairly high doses of β-blockers. No significant rebound phenomenon appears to occur on withdrawal of calcium antagonists.
Aspirin (325 mg/day) has been shown to reduce by 50% the rate of myocardial infarction and death in patients wilh unstable angina, to provide secondary prevention after myocardial infarction, and to improve patency of saphenous vein grafts after bypass surgery.

The prevalence and severity of coronary artery disease increase dramatically with age. The increase is greater in men than in women and reaches a peak between the sixlh and sevenih decade, at which point it declines slightly. The increase in women continues steadily until Ihc eighth decade. The prevalence is about 60% in both sexes at the eighth decade and thereafter. Despite the high prevalence of coronary artery disease in the elderly, symptomatic disease is noted in only 10% to 20% of this population. This discrepancy may be due to (1) decreased activity levels (work loads that would ordinarily trigger ischemic symptoms may be encountered less frequently in the elderly), (2) increased likelihood of a neuropathy that alters pain sensation, or (3) age-associated myocardial and possibly pericardial changes, making dyspnea more likely to occur than chest pain when ischemia is present. The prevalence of disease detected on thallium stress testing also increases, from 2% in the fifth and sixth decades to > 25% in the ninth decade.
Diagnosis
(See also Ch. 34)
Coronary artery disease should be strongly suspected in persons with known coronary risk factors (see Prevention, below) and in those with signs of noncoronary atherosclerosis, such as cerebrovascular or peripheral vascular disease. The probability of disease (which is higher in an elderly person), as well as the sensitivity and specificity of a test (see TABLE 34-1), determine a test’s accuracy. Thus, a positive test result is more predictive, and a negative result less so. in an older person.
Exercise stress testing is useful for diagnosing coronary artery disease and for predicting subsequent coronary death in middle-aged persons with two or more risk factors. It is probably equally useful in the elderly (see TABLE 34-2). Exercise stress testing is also used to evaluate the severity of coronary artery disease. Left main artery or triple-vessel obstructions typically produce systolic hypotension (a fall in systolic blood pressure of > 15 mm Hgfrom one exercise level to the next) as well as several types of ECG changes. These include global changes (te, those occurring in both the anterior and inferior leads), marked changes (> 2 mm of ST-segment shift), prolonged changes (those persisting > X min after exercise), early changes (those occurring during stage 1 or stage 2 of the standard Bruce treadmill test), and the appearance of malignant ventricular arrhythmias.
Two points should be considered when evaluating a stress ECG. First. ST and T changes cannot be interpreted if a person has left bundle branch block or left ventricular hypertrophy or is taking digoxin, all of which are more likely in older than in younger persons. Under these circumstances, thallium stress testing is a better alternative. Second, older patients often cannot exercise to 90% of predicted maximum heart rate because of respiratory or musculoskeletal disease. In older persons who cannot exercise to Ihe desired heart rale or work load, thallium scan or ECG testing after the administration of a pharmacologic stress such as dipyridamole or adenosine may be used to diagnose significant coronary artery disease. Adenosine probably has a greater incidence of side effects, such as impulse formation or conduction system disturbances. Pacing may also be used to increase the heart rate and so induce ischemia in appropriate patienls. However, not only is insertion of ii pacemaker an invasive procedure, but the stress provoked by pacing is often not comparable to that induced by exercise.
In addition lo scintigraphic and ECG evidence of ischemia, functional evidence may be provided by echocardiography. Echocardiography performed during dobutaminc infusion and then during or immediately after exercise can help diagnose, localize, and assess the seventy of ischemia-induced left ventricular dysfunction. The diagnostic sensitivity and specificity are similar lo those of other imaging modalities. Advantages include using less expensive technology and avoiding radiation exposure.
Prevention
The principles of coronary artery disease management are similar for all patients, and risk factor modification may be as important in older patienls as in younger ones. Measures should be taken to decrease the progression of coronary atherosclerosis in both symptomatic and asymptomatic elderly persons.
Data from the Framingham Heart Study indicate that systolic blood pressure is the strongest discriminator of coronary artery disease risk in men > 45 yr old. A study of persons > 60 yr of age with isolated systolic hypertension (systolic pressure i≥ 160 mm Hg without diastolic hypertension) has shown that treatment decreases the risk of major cardiovascular outcomes.
Total cholesterol levels have been related to unfavorable cardiovascular outcomes in the elderly, although not in the Framingham data. High levels of low-density lipoprotein (LDL) cholesterol represent a significant risk factor for cardiovascular disease; conversely, high levels of high-density lipoprotein (HDL) cholesterol are associated with reduced risk. Drug and dietary interventions lo lower LDL levels have been shown to reduce cardiovascular risk in middle-aged populations. Although similar data are not available for the elderly, recommending dietary changes and pharmacotherapy for older persons with coronary artery disease and abnormal lipid levels is probably prudent (see also Ch. HI).
Many studies correlate cigarette smoking with increased cardiovascular risk in the elderly. Studies also show that cessation of smoking for as little as 1 to 5 yr markedly reduces risk.
Physical inactivity is an additional risk factor fur Ihe development of coronary artery disease. The benefits of exercise may be related to maintenance of normal blood pressure, a favorable influence on the lipid profile, decreased neurohumoral activation, and improved glucose tolerance. However, since asymptomatic disease is so prevalent in the elderly, older persons should undergo a supervised exercise test before initiating, and at regular intervals while participating in, a regular exercise program (sec Ch. 31).

A condition in which one or more of the coronary arteries is narrowed by atherosclerotic plaque or vascular spasm.
Coronary artery disease reflects an imbalance between myocardial oxygen supply and demand. This imbalance, which represents myocardial ischemia, is expressed clinically as angina or myocardial infarction. Most sudden cardiac deaths are arrhythmic secondary to coronary artery disease.