Most of the major adverse effects of beta blocking drugs result from beta-adrenoreceptor blockade. Many signs and symptoms can therefore be induced because the beta receptors affect multiple metabolic and physiologic functions. Other reactions apparently unrelated to beta blockade can occur, but they are uncommon.
The major side effects associated with the use of beta blockers will be reviewed here. Beta blocker intoxication (overdose) and the clinical use of these drugs for the treatment of arrhythmias, hypertension, myocardial infarction, and heart failure are discussed separately. (See "Beta blocker poisoning" and "Choice of drug therapy in primary (essential) hypertension: Recommendations", section on 'Beta blockers' and "Acute myocardial infarction: Role of beta blocker therapy" and "Use of beta blockers in heart failure due to systolic dysfunction".)
ADVERSE CARDIAC EFFECTS DUE TO BETA BLOCKADE
Major cardiac effects caused by beta blockade include the precipitation or worsening of congestive heart failure, and significant negative chronotropy.
Heart failure — Despite the data about the importance of beta blockers as long-term therapy for patients with chronic heart failure, beta blockers may exacerbate heart failure in patients with acute decompensated or precipitate heart failure in those with preexisting myocardial dysfunction and borderline compensation since the maintenance of cardiac output in such patients depends in part upon sympathetic drive. Increased peripheral vascular resistance, induced by nonselective beta blockers, also may contribute to the decline in myocardial function in this setting. On the other hand, drugs with intrinsic sympathetic activity (ISA), such as pindolol, may be less likely to impair myocardial function .
Despite these concerns, only a minority of patients with stable heart failure deteriorate after the initiation of beta blocker therapy. As an example, worsening of heart failure was observed in only 6 percent of patients with chronic heart failure who were being treated with carvedilol . Furthermore, long-term therapy with beta blockers is often beneficial in such patients, improving survival in patients with systolic heart failure and improving diastolic function in patients with diastolic heart failure. (See "Use of beta blockers in heart failure due to systolic dysfunction" and "Treatment and prognosis of diastolic heart failure".)