Use of Calcium Blockers in Patients with Unstable Angina

The Big Heart Disease Lie

Foods to help when you have Heart Disease

Get Instant Access

Several small randomized trials have examined the use of nifedipine and diltiazem in unstable angina. A meta-analysis of these trials (37) showed no reduction in MI or death rates in patients given calcium antagonists (110 of 561 patients [20%] treated with calcium antagonists developed MI, compared to 104 of 548 [19%] in the control group; death rates were 2.4 and 1.6% for the calcium antagonist and control groups, respectively) (Fig. 5). The largest trial, the Holland University Nifedipine/Metoprolol Trial (HINT) (31) described above, was discontinued prematurely because of a trend toward more nonfatal MIs in patients receiving nifedipine alone. When combined with a P-blocking agent, however, patients receiving nifedipine had a decreased rate of MI and death compared with placebo.

Pulmonary Imfarction

Fig. 6. Diltiazem-treated patients with pulmonary congestion had a higher rate of cardiac events than patients receiving placebo; diltiazem-treated patients without pulmonary congestion had a lower rate of cardiac events than patients receiving placebo. The values in parentheses are numbers of patients.

Fig. 6. Diltiazem-treated patients with pulmonary congestion had a higher rate of cardiac events than patients receiving placebo; diltiazem-treated patients without pulmonary congestion had a lower rate of cardiac events than patients receiving placebo. The values in parentheses are numbers of patients.

Several studies, however, have shown symptomatic benefit from calcium antagonists (50-52). Thus, evidence for calcium channel blockers in unstable angina does not suggest any beneficial effect on mortality or progression of MI, but does support their use for relief of refractory symptoms. Because of randomized trials showing an increased risk of death in patients treated with calcium channel blockers in the setting of AMI, particularly in patients with LV dysfunction (49), calcium antagonists should be used only in patients with refractory symptoms despite the use of nitrates and b-blockers.

Calcium blocking agents have also been used successfully to reduce symptoms and possibly decrease morbidity in patients with vasospastic (also known as Prinzmetal's or variant) angina (53-56). Although patients with either Prinzmetal's variant angina or unstable angina may present with rest angina, patients with Prinzmetal's angina are characterized by preservation of exercise capacity without angina. By contrast, patients with unstable angina, who usually have severe epicardial coronary plaques that reduce blood flow, typically have very limiting exertional angina, as well as rest angina. In several small controlled and uncontrolled trials, a significant reduction in angina frequency was reported with the use of calcium antagonists (53-55). There are no data to suggest superior efficacy of any one agent in particular. In one very small trial of patients with refrac-

Table 5

Recommendations for the Use of Calcium Blocker Therapy for the Acute Coronary Syndromes3

Conditions for which there is evidence that treatment is beneficial, useful, and effective.

Verapamil or diltiazem may be given to patients in whom b-adrenoceptor blockers are ineffective or contraindicated (i.e., bronchospastic disease) for relief of ongoing ischemia or control of a rapid ventricular response with atrial fibrillation after AMI in the absence of CHF, LV dysfunction, or AV block.

Conditions for which beneficial effects are less well established.

In non-ST-elevation infarction, diltiazem may be given to patients without LV dysfunction, pulmonary congestion, or CHF; it may be added to standard therapy after the first 24 h and continues for 1 yr.

Conditions for which evidence suggests treatment is not useful and may be harmful.

Nefedipine (short-acting) is generally contraindicated in routine treatment of AMI because of its negative inotropic effects and the reflex sympathetic activation, tachycardia, and hypotension associated with its use.

Diltiazem and verapamil are contraindicated in patients with AMI and associated LV dysfunction or CHF.

aAbbreviations: AMI, acute myocardial infarction; CHF, congestive heart failure; LV left ventricular.

Data from ref. 15.

tory angina, the combination of diltiazem and nifedipine was more effective than either agent alone (55), although intolerable side effects precluded the use of both drugs in several of these patients. Because vasospastic angina is due to transient coronary arterial spasm rather than plaque rupture and thrombus, there is no role for antithrombotic or antiplatelet agents. Medical therapy, with an emphasis on nitrates and calcium antagonists titrated to symptom relief, is the mainstay of treatment. However, because most patients with vasospastic angina have some degree of underlying epicardial coronary artery disease, they may occasionally present with AMI due to plaque rupture. These patients should be managed according to standard practice.

The most recent ACC/AHA guidelines concerning use of the calcium channel blockers are shown in Table 5 (15).

Was this article helpful?

0 0
Your Heart and Nutrition

Your Heart and Nutrition

Prevention is better than a cure. Learn how to cherish your heart by taking the necessary means to keep it pumping healthily and steadily through your life.

Get My Free Ebook


Post a comment