Coronary Artery Calcium

Abstract

Surrogate markers of atherosclerosis such as treadmill time, serum tests, coronary artery calcium, and carotid intimal thickness enjoy considerable attention and the promise of yielding answers at much less cost and time than clinical trials using hard clinical outcomes such as myocardial infarction and cardiac death. Indeed, only studies with large sample sizes and long follow-up periods can provide meaningful data on hard outcomes. Of course, from a patient care perspective, the value of a surrogate marker derives solely from its ability to predict a cardiac event giving rise to either death or physical impairment that could be prevented. What is important to patients is whether a new therapy can make one feel better or live longer (or both). Few patients would eagerly undergo a new treatment if it would merely change a measurement but would not also improve how they felt, would not reduce their risk of heart attacks, and/or would not help them to live longer. Article p 427 Cardiologists’ recent experience with hormone replacement therapy (HRT) once again illustrated the dangers of relying too heavily on surrogate markers. Multiple studies of HRT using surrogate markers showed a benefit on cardiovascular disease.1 The Postmenopausal Estrogen/Progestin Intervention (PEPI) trial, for example, showed that HRT had beneficial effect on serum markers of atherosclerosis, with lower low-density lipoprotein (LDL) and fibrinogen levels and higher high-density lipoprotein.2 The Rancho Bernado Study found that women taking HRT had lower coronary artery calcium (CAC) scores and concluded that there was antiatherogenic effect of postmenopausal estrogen (but nevertheless called for …