Coronary Artery Disease: When Plaques AttackPage 11 of 12

9. Summary

Causes and Symptoms of Angina

When a person’s epicardial heart arteries contain significant atherosclerosis, the condition is called coronary artery disease. Coronary artery disease is the number one killer of Americans, accounting for 1 of every 4 deaths.

Patients with CAD can be asymptomatic. As the disease progresses, however, it often produces angina pectoris. Angina pectoris, or simply angina, is the chest discomfort caused by ischemic heart muscle. The feeling of angina is typically described as a substernal pressure, tightness, heaviness, or suffocation rather than as pain; sometimes, the discomfort of angina is felt in an arm, a shoulder, the neck, or the jaw. Instead of angina, patients may experience anginal equivalents, such as shortness of breath or fatigue that follow a pattern typical of angina.

Angina that appears at a predictable level of exercise and that is relieved by rest or nitroglycerin is a characteristic of the form of CAD called stable angina. When the angina becomes unpredictable, the disease has moved to a form called unstable angina. Brief (<10 minutes) angina that is relieved by rest usually indicates an ischemic episode without significant heart damage. Extended angina (>20 minutes) usually indicates an MI, which means that some heart muscle has died (myocardial necrosis).

Acute Complications of CAD

Unstable angina can present as an acute coronary syndrome. An acute coronary syndrome is an episode of angina that is unusually severe, that is not relieved by rest or nitroglycerin, or that lasts >20 minutes. An acute coronary syndrome signals heart ischemia that may be severe enough to cause an MI, and a patient with an acute coronary syndrome should immediately be taken to an emergency department.

The damage done by major heart ischemia can be reduced significantly if the blood supply to the heart is restored by cardiac reperfusion therapy within about an hour. A more modest recovery of ischemic muscle can be achieved by reperfusion therapies done between 2 and 12 hours after the beginning of an MI. The two forms of immediate reperfusion therapy are percutaneous coronary interventions (angioplasty with or without stenting) and IV injections of fibrinolytic agents.

The acute coronary syndrome patients who are most likely to benefit from an aggressive reopening of the obstructed coronary arteries are those in whom the ischemia affects a large region of muscle or in whom an entire cross section of heart wall has become ischemic (transmural ischemia).

Blood tests and ECGs are used to identify candidates for reperfusion. The appearance of cardiac biomarkers (eg, cardiac troponins) in the bloodstream is a reliable sign of an MI. The appearance of elevations in the ST-segment of the patient’s ECG waveform suggests that the area of the infarction is large or transmural. Together, these results indicate that immediate reperfusion therapy would be appropriate.

A systematic checklist for managing an acute coronary syndrome includes:

  • Patients with worrisome chest discomfort should be taken to an emergency department immediately.
  • After being stabilized, patients should chew 162 to 325 mg aspirin, blood tests for cardiac biomarkers should be analyzed, and ECGs evaluated. Patients with ECG changes indicating an acute ST-elevation myocardial infarction (STEMI) are candidates for immediate reperfusion therapy.
  • All patients with a possible acute coronary syndrome should have pain relief (usually, nitroglycerine, with or without morphine). Patients with acute coronary syndromes are given a beta blocker, and patients with heart failure may receive an ACE inhibitor.
  • A combination of antiplatelet/anticoagulant therapy and cardiac monitoring is the next step for those acute coronary syndrome patients who will not have reperfusion therapy.
  • Patients with no elevation of their cardiac biomarkers and with a normal or nearly normal ECG should be treated with sublingual nitroglycerin. Depending on the circumstances, morphine and oral beta blockers might also be administered. If the heart symptoms resolve and the patient improves, continued treatment with antiplatelet medications is considered.
  • Begin (or continue) patients on a cardiac rehabilitation program. (Brady et al., 2009)

Management of CAD

Coronary artery disease will always benefit from therapeutic lifestyle changes that can slow, stop, or occasionally reverse atherosclerosis. These lifestyle changes include a low-fat/high-fiber diet, weight loss, increased physical activity, and smoking cessation.

Management of CAD also includes controlling problematic co-existing disorders. Blood lipids should be kept in safe ranges:

  • LDL cholesterol <100 mg/dl (<70 mg/dl in patients with significant artery disease)
  • Triglycerides <150 mg/dl, HDL cholesterol >40 mg/dl in men and >50 mg/dl in women
  • Blood pressure lower than systolic 140 mm Hg and diastolic 90 mm Hg

Lower pressures are better, and a reduction to a systolic pressure <130 mm Hg and a diastolic pressure <80 mm Hg is often advised. Angina indicates heart ischemia. Typical angina can be relieved by rest and by sublingual nitroglycerin tablets. Patients with stable angina can often avoid heart symptoms by slowing the rate at which they do their normal daily activities. When certain unavoidable activities cause angina, the angina can be reduced by taking a sublingual nitroglycerin tablet 5 minutes before the stressful activity.

A systematic checklist for managing CAD includes:

  • Institute a prophylactic drug regimen of nitroglycerin, beta blockers, aspirin and, when needed, ACE inhibitors.
  • Ask the patient to keep a record of symptom triggers, symptom details, and the success or failure of symptom relievers.
  • Consider coronary angiography if symptoms interfere with the patient’s daily activities.

Cardiac Rehabilitation

Long-term treatment for patients who have had an acute coronary syndrome is called secondary prevention, or cardiac rehabilitation. The goal of cardiac rehabilitation is to reduce the patient’s chances of another acute coronary syndrome and to strengthen the cardiovascular system so the patient can resume normal daily activities.

Cardiac rehabilitation attempts to reduce the same atherosclerotic risks that are the subjects of primary treatment. Similar lifestyle changes and medications are recommended for rehabilitation and for primary treatment, although cardiac rehabilitation usually includes a more aggressive antithrombotic drug regimen.

The restrengthening component of cardiac rehabilitation consists of a gradually increasing exercise program that is initially supervised. By 6 months to 1 year, the supervised program should evolve into a lifetime of patient-directed regular exercise, along with weight watching and healthy eating.