A Review of Why and How We May Use β-Blockers in Congestive Heart Failure: Ischemic vs Idiopathic DCM and β-Blockers
Two of the negative studies had a duration of only 1 month, during which time there may be temporary deterioration. Although a few patients have immediate improvement, it usually takes 2 months for an increase in ejection fraction, and 6 months to a year for maximum response. After many months, a larger dose may produce an even greater increase in ejection fraction. Sackner-Bernstein and colleagues in a 1995 abstract, showed that of 18 patients whose CHF worsened during the initial 3 to 5 weeks of β-blocker therapy, subsequent improvement occurred over the next 4 months similar to the patients who had had no early worsening. Fortunately, to our knowledge, there are no reported deaths directly attributable to this acute intolerance that occurs in as high as 7% of patients. buy yasmin online
Ischemic vs Idiopathic DCM and β-Blockers
Several studies have shown that although patients with either idiopathic or ischemic types of DCM showed improvement while receiving β-blockers, the idiopathic types had a significantly better response. Fisher et al and Maisel found that if the cardiomyopathy was ischemic, those with high norepinephrine levels or very low ejection fractions were far more likely to respond to metoprolol. The nonspecific β-blocker carvedilol with its vasodilating properties caused improvement in ejection fraction in both ischemic and idiopathic DCM. In 1995, an Australia-New Zealand group study gave carvedilol only to patients with ischemic DCM. There was an improved ejection fraction, and after 18 months, there were fewer hospitalizations and deaths (Table 5). When Woodley and colleagues in 1991 gave the β-blocker bucindolol, which also had vasodilatory properties (nitrile group mediated), it caused significant improvement only in patients with idiopathic DCM (Table 4). In a 1993 Belgian study on 20 patients with ischemic DCM and low ejection fractions (between 25% and 50%), they found that after 2 months of the β-blocker nebivolol vs atenolol, there was an increased ejection fraction after 2 months with both drugs.