Annotation L

OBJECTIVE

Assure appropriate treatment with beta-blockers in patients with prior MI.

ANNOTATION

Adjust Angina Management , If Indicated

Three classes of drugs are available for the control of symptoms in patients with chronic stable angina: beta-adrenergic blocking agents, calcium channel blocking agents, and nitrates.

Beta-adrenergic blocking agents are generally considered the first drug of choice because of: (1) the documented survival benefit in patients with prior MI, and (2) a survival benefit in patients with hypertension. Beta-adrenergic blocking agents also reduced morbidity from stroke and heart failure in patients with hypertension . Beta-adrenergic blocking agents probably achieve their antianginal effect primarily through slowing of the heart rate and to a lesser extent from reduction in systolic pressure and contractility. Therefore, a commonly used “rule of thumb” is to titrate the beta-blocker to angina relief or to a resting heart rate of 55 to 60.

Patients with prior MI, treated with adequate doses of beta-blockers, have reduction in recurrent events and mortality. Every effort should be made to use this class of drugs in these patients in particular but also in all patients with documented IHD. Physicians may overrate contraindications to using beta-blockers in post-MI patients (i.e., diabetes, lower EF, depression, and chronic obstructive pulmonary disease (COPD)). In fact, patients with diabetes and lower EF have proven benefits from beta-blockers post-MI and patients with COPD can often tolerate beta-blockers. The association between depression and beta-blockers has been questioned (see the following Discussion section). In general, the decision to avoid beta-blockers, based on theoretical concerns, should be carefully weighed against the overwhelming evidence supporting their use in patients with CAD.

Overviews of multiple randomized trials indicate that beta-adrenergic blocking agents and calcium channel-blocking agents are equally effective in providing angina relief and in enhancing exercise duration to 1 mm ST-segment depression (Figures 9 and 10, ACC/AHA Stable Angina Guidelines, 1999). Therefore, in patients without prior MI or hypertension, a long-acting calcium channel agent would be acceptable. However, there is ongoing controversy about whether the short-acting calcium channel drugs are associated with increased morbidity and mortality.

Sublingual nitroglycerin has been used in the treatment of angina for more than two hundred years. It is still the mainstay therapy for the immediate relief of angina that has been provoked by exertion or emotion. Furthermore, sublingual nitroglycerin, when taken prior to an activity that commonly causes angina (e.g., walking up stairs or up hill) will often prevent the development of symptoms. Several forms of longer acting nitrates (e.g., isosorbide dinitrate and isosorbide mononitrate, and topical nitroglycerin patches) are also commonly used for prophylaxis of angina. However, care must be taken to ensure a nitrate-free interval of 8 to 12 hours out of every 24, to prevent the development of tolerance. The use of a nitrate preparation within 24 hours of the use of sildenafil (Viagra) may cause dangerous hypotension.

DISCUSSION

An association between depression and beta-blocker use has been assumed, but evidence is lacking. Unfortunately, much of the literature on this topic is based on case reports or series. Use of pharmacy claims data have yielded conflicting results. Bright et al. (1992) found no association between beta-blockers and prescriptions for antidepressant drugs or hospitalization for depression, in a large study of Medicaid claims data. Gerstman et al. (1996) found no difference in incidence of depression with beta-blockers and other anti-hypertensive agents. In a systematic review of the literature, Ried et al. (1998) concluded that studies using a diagnosis of depression generally do not support an association between beta-blockers and depression, but studies of pharmacy data support the hypothesis. Until definitive studies further clarify a significant association between beta-blockers and depression, clinicians should carefully weigh the evidence for and against using this drug class for individual patients with concomitant depression and CAD.