Chapter 6: Chronic Ischemic Heart Disease

Introduction

General Considerations

For clinical purposes, patients with chronic ischemic heart disease fall into two general categories: those with symptoms related to the disease, and those who are asymptomatic. Although the latter are probably more common than the former, physicians typically see symptomatic patients more frequently. The issue of asymptomatic patients becomes important clinically when physicians are faced with estimating the risk to a particular patient who is undergoing some stressful intervention, such as major noncardiac surgery. Another issue is the patient with known coronary artery disease who is currently asymptomatic. Such individuals, especially if they have objective evidence of myocardial ischemia, are known to have a higher incidence of future cardiovascular morbidity and mortality. There is, understandably, a strong temptation to treat such patients, despite the fact that it is difficult to make an asymptomatic patient feel better, and some of the treatment modalities have their own risks. In such cases, strong evidence that longevity will be positively influenced by the treatment must be present in order for its benefits to outweigh its risks.

Pathophysiology & Etiology

In the industrialized nations, most patients with chronic ischemic heart disease have coronary atherosclerosis. Consequently, it is easy to become complacent and ignore the fact that other diseases can cause lesions in the coronary arteries (Table 6–1). In young people, coronary artery anomalies should be kept in mind; in older individuals, systemic vasculitides are not uncommon. Today, collagen vascular diseases are the most common vasculitides leading to coronary artery disease, but in the past, infections such as syphilis were a common cause of coronary vasculitis. Diseases of the ascending aorta, such as aortic dissection, can lead to coronary ostial occlusion. Isolated coronary artery dissection can also occur. Coronary artery emboli may occur as a result of infectious endocarditis or of atrial fibrillation with left atrial thrombus formation. Infiltrative diseases of the heart, such as tumor metastases, may also compromise coronary flow. Therefore, it is essential to keep in mind diagnostic possibilities other than atherosclerosis when managing chronic ischemic heart disease.

Myocardial ischemia is the result of an imbalance between myocardial oxygen supply and demand. Coronary atherosclerosis and other diseases reduce the supply of oxygenated blood by obstructing the coronary arteries. Although the obstructions may not ...