Calcium-Channel Blockers No Better Than Diuretics for Treating Hypertension

Diuretics are just as effective as calcium-channel blockers, alpha-blockers or angiotensin-converting enzymes (ACE) inhibitors when treating hypertension among patients with metabolic syndrome, according to a report in the Archives of Internal Medicine.

Metabolic syndrome is defined as hypertension with at least two of the following factors: high glyceride levels, diabetes, a body mass index (BMI) of at least 30, and low levels of "good cholesterol." Patients with metabolic syndrome are at high risk for complications of cardiovascular disease.

While some alpha-blockers, ACE inhibitors and calcium channel blockers have more favorable short-term effects on blood glucose or blood cholesterol levels, they have been promoted over beta-blockers and diuretics to treat patients with metabolic syndrome.

Researchers at Case Western Reserve University, Cleveland, analyzed data from the Antihypertensive and Lipid- Lowering Treatment to Prevent Heart Attack Trial (ALLHAT). 42,418 hypertension patients with at least one other risk factor for heart disease were randomly picked to take either a diuretic (chlorthalidone -15,255 patients), a calcium channel blocker (doxazosin mesylate – 9,061 patients), or an ACE inhibitor (lisinopril – 9,054 patients).

Other drugs could be added if necessary to control blood pressure, and patients were checked for an average of 4.9 years for all drugs administered except the alpha-blocker. Followup of this drug was discontinued after 3.2 years, because increased rates of cardiovascular disease were noted, including nearly twice the rate of heart failure, compared with the group taking diuretics. A total of 23,077 ALLHAT participants (54.4%) met criteria for metabolic syndrome.

"No differences were noted among the four treatment groups, regardless of race or metabolic syndrome status for the primary end point (non-fatal myocardial infarction [heart attack] and fatal coronary heart disease)," the authors write.

Among patients with the metabolic syndrome (7,327 black and 15,750 white patients), the calcium channel blocker, ACE inhibitor and alpha-blocker had higher rates of heart failure compared with the diuretic; the ACE inhibitor and the alpha-blocker also had an increased risk of combined cardiovascular disease.

"The lack of benefit of the agents with the most favorable metabolic profile (i.e., ACE inhibitors and alpha-blockers) was especially marked in the black participants with metabolic syndrome," the authors write. "The magnitude of the excess risk of end-stage renal disease (70 percent), heart failure (49 percent) and stroke (37 percent) and the increased risk of combined cardiovascular disease and combined coronary heart disease strongly argue against the preference of ACE inhibitors over diuretics as the initial therapy in black patients with metabolic syndrome. Similar higher risk was noted for those randomized to the alpha-blocker vs. the diuretic."

"These findings fail to provide support for the selection of alpha-blockers, ACE inhibitors, or calcium channel blockers over thiazide-type diuretics to prevent cardiovascular or renal outcomes in patients with metabolic syndrome, despite their more favorable metabolic profiles," the authors conclude.

This study was supported by a contract from the National Heart, Lung, and Blood Institute and by Pfizer Inc. (ALLHAT).

Source: Arch Intern Med. 2008;168[2]:207-217.