Calcium channel blockers are a diverse and widely used class of medications for patients with hypertension, ischemic heart disease and certain arrhythmias. All calcium channel blockers dilate coronary and peripheral blood vessels. Recent case control studies have raised concern about increased cardiovascular mortality in patients with hypertension who are receiving calcium channel blockers (particularly short-acting forms) when compared with patients receiving other antihypertensive medications. Given the large number of patients taking these medications, it is important to determine if there is in fact a specific risk associated with the use of calcium channel blockers. Michels and associates performed a prospective study to determine if there is an increased risk of cardiovascular disease and mortality in patients with hypertension who took calcium channel blockers compared with patients who used other antihypertensive medications.
A total of 14,617 women from 30 to 55 years of age who had hypertension and regularly used antihypertensive medications were observed over a six-year period. A first fatal or nonfatal cardiovascular event (234 myocardial infarctions, 162 strokes and 12 sudden deaths) occurred in 385 women during this period. Women who used calcium channel blockers alone had an age-adjusted relative risk of myocardial infarction of 2.36 compared with women receiving thiazide diuretics alone.
Adjustment for coronary disease risk factors decreased the association considerably, but it still remained elevated. Women receiving calcium channel blocker therapy had a relative risk of 1.64 compared with a 1.88 relative risk in women receiving combination therapy.
The authors found a significant elevation in the relative risk of total myocardial infarction among women who used a calcium channel blocker compared with those who did not. However, it remains unclear if the elevation in risk for myocardial infarction among women who use calcium channel blockers is real or a result of confounding factors based on study methodologies.
Clinical trials comparing long-acting calcium channel blockers against other antihypertensive agents (notably thiazide diuretics and beta blockers) are currently under way. Until more data are available, the authors advise following the recommendations of the Sixth Report of the Joint National Committee on the Detection, Evaluation, and Treatment of High Blood Pressure. Specifically, diuretics and beta blockers should be considered “first-line” choices for hypertension therapy, and calcium channel blockers should be reserved for special indications (e.g., isolated systolic hypertension in older patients who do not respond to thiazide diuretics).