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Edie Earl: Discussion

Edith is experiencing palpitations, defined as an increased awareness of the beating heart. The intermittent sensation of a pause followed by an accentuated beat is consistent with a ectopic beats rather than a sustained arrhythmia. The physical exam indicates that the heart is normal and the EKG subsequently shows a premature contraction. The wide QRS and the long (compensatory) pause after the premature beat indicate a premature ventricular contraction (PVC).

Premature ventricular contractions (PVCs) have been studied intensively in the medical literature. PVCs occur in approximately 1 per cent of normal individuals as determined by standard EKG and in many as 75% as determined by Holter monitor. It is generally assumed that PVCs are benign in younger individuals, less than 30 years of age. They are often associated with stimulants such as caffeine, alcohol, or tobacco and sometimes with non-cardiac intercurrent illnesses such as influenza or bacterial pneumonia.

With advancing age, PVCs increase in prevalence and may be associated with a higher risk for underlying heart disease, myocardial infarction, and sudden death.

The Tecumseh study (1), published in 1969, determined that the rate for sudden death in unscreened individuals age 30 and above with PVCs was 6% versus a rate of 1% for individuals without PVCs. Even in the 30-39 year-old age group the sudden death rate for those with PVCs was nearly 5 times that of those without PVCs. In contrast, a later study of patients referred to a Washington University cardiology clinic because of frequent and complex ventricular ectopy (2) determined that the overall death rate for this group was less than the general population, and that the sudden death rate of 1.3% was about equal to that of a cohort of individuals with no or mild coronary disease. The Tecumseh study stated that "ventricular premature systoles increase the risk of sudden death among persons with overt or subclinical heart disease." The St. Louis study concluded that "the long-term prognosis in asymptomatic healthy subjects with frequent and complex ventricular ectopy is similar to that of the healthy U.S. population and so suggests no increased risk of death." Of interest, the PROMISE study (3) recently concluded that "ventricular arrhythmias do not specifically predict sudden death in patients with moderate-to-severe heart failure." PVCs should be distinguished from ventricular tachycardia (a sequence of ventricular premature beats) which is a definite risk factor for sudden death in individuals with diminished ventricular function.

In practice, PVCs are generally considered to be benign, especially in younger indivivduals. In "older" individuals (e.g. above age 30) PVCs may predict underlying heart disease but do not effect prognosis unless they are associated with ventricular tachycardia in a setting of diminished ventricular function.

Another dimension to Edith's case is her competitive running. Does this place her at increased risk for a cardiac event? It is estimated that the incidence of sudden deaths on athletic fields is 1:100,000 to 1:300,000 for high school age athletes, rising in older age groups to 1:50,000 marathoners and 1:15,000 joggers. Most deaths in younger athletes, under age 35, are due to congenital disorders. Hypertrophic cardiomyopathy is responsible for about one third to one half of cases (4).

The next most common cause is congenital coronary anomalies, particularly anomalous origin of the left main coronary artery from the right sinus of Valsalva. Less common causes in younger athletes include ruptured aorta associated with Marfan's syndrome, mitral valve prolapse, aortic stenosis, myocarditis, idiopathic left ventricular hypertrophy, and premature coronary disease. The two common conditions, hypertrophic cardiomyopathy and anomalous origin of the coronary artery are usually asymptomatic. Hypertrophic cardiomyopathy, and sometimes anomalous coronary arteries, can be diagnosed with the 2D echocardiogram.

The principal cause of sudden death in older athletes is coronary artery disease. The American Heart Association currently recommends that competitive athletes have a preparticipation examination with a clinician. The examination should include an interview and physical examination. If abnormalities such as chest pain, dyspnea, palpitations, or murmurs are detected the athlete should be referred to a cardiologist. Screening of asymptomatic individuals with normal physical examinations with an ECG or echocardiogram is not recommended. (5).

It is unlikely that Edith's PVCs are associated with heart disease or increased risk for sudden death. However, there is some uncertainty with respect to risk. A reasonable approach would be for Edith first to eliminate caffeine. If the PVCs persist an echocardiogram and Holter monitor would be prudent if she wishes to continue to run.

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