Circulation. Heart failure
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Randomized Controlled Trial
Effect of β-blocker cessation on chronotropic incompetence and exercise tolerance in patients with advanced heart failure.
Chronotropic incompetence is defined as the inability to reach 80% of heart rate (HR) reserve or 80% of the maximally predicted HR during exercise. The presence of chronotropic incompetence is associated with reduced peak oxygen consumption, and rate-responsive pacing therapy is under investigation to improve exercise capacity in heart failure (HF). However, uncertainty exists about whether chronotropic incompetence and reduced exercise tolerance in HF are attributable to β-blockade. ⋯ Acute β-blocker cessation does not normalize the chronotropic response to exercise in patients with advanced HF and chronotropic incompetence.
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Randomized Controlled Trial
Mineralocorticoid receptor antagonists and cardiovascular mortality in patients with atrial fibrillation and left ventricular dysfunction: insights from the Atrial Fibrillation and Congestive Heart Failure Trial.
Patients with heart failure (HF) and atrial fibrillation (AF) may differ from the larger HF population with respect to comorbidities, including renal impairment and overall prognosis. Associated cardiorenal interactions may mitigate the effects of pharmacological agents. Our primary objective was to assess the impact of mineralocorticoid receptor antagonists on cardiovascular mortality in patients with AF and HF enrolled in the Atrial Fibrillation and Congestive Heart Failure (AF-CHF) trial. ⋯ Renal dysfunction was highly prevalent in patients with AF and HF. Mineralocorticoid receptor antagonists were independently associated with an increased incidence of cardiovascular deaths, predominantly of presumed arrhythmic cause. Although these provocative findings merit prospective validation, they underscore the importance of careful monitoring of renal function and electrolytes in patients with AF and HF receiving mineralocorticoid receptor antagonists.