Cardiac conduction with diltiazem and beta-blockade combined. A review and report on cases

Sinus arrest or atrioventricular block are rare but serious adverse effects of diltiazem. The risk of developing such adverse reactions may be somewhat exacerbated by concomitant beta-adrenergic blocker therapy. In patients with hypertension or coronary heart disease, combination therapy with diltiazem and a beta-blocker usually enhances therapeutic benefit relative to monotherapy, but adverse effects attributable to this combination, especially in patients with left ventricular dysfunction or latent cardiac conduction deficits, may be limiting. Therefore, such combination therapy may not be suitable in patients with atrioventricular block grade I, bradycardia or hypotension, and patients on the combined therapy should always have their blood pressure, heart rate and atrioventricular conduction on ECG monitored. If combination therapy with diltiazem and propranolol or metoprolol is commenced, or in the case of impaired renal function, an adjustment of the beta-blocker dosage may be required. Clinical studies on the combined use of diltiazem and beta-adrenergic blockers mostly concern the treatment of angina pectoris in patients with coronary heart disease. Although very few cases of severe bradycardia and conduction abnormalities have been reported in patients with uncomplicated hypertension on diltiazem and beta-blockade combination, there seems to be a potential for the occurrence of significant conduction disturbances with the combined treatment, and precautions should apply also for hypertensive populations.