Two cases of dilated cardiomyopathy with blood pressure-limited tolerability of cardioprotective agents improved by ivabradine

The titration of cardioprotective agents is essential for successful treatment of heart failure (HF) patients with reduced left ventricular ejection fraction. However, hypotension is one of the limiting factors for titration. Ivabradine reduces heart rate without compromising systolic function by prolonging diastolic filling time. Herein two cases of dilated cardiomyopathy (DCM) are presented in which ivabradine improved blood pressure (BP)-limited tolerability and allowed for further titration of cardioprotective agents. In both cases, the introduction of ivabradine raised the BP, which permitted further increase of the dose of renin-angiotensin system inhibitors or beta-blockers. One major hypothesized mechanism of ivabradine-induced BP elevation has been postulated to be an increase in stroke volume due to prolonged ventricular diastolic filling time. However, ivabradine is not expected to increase BP for all HF patients. In those with small and poorly compliant ventricles with severe diastolic or restricted dysfunction, decreased heart rate and prolonged diastole may excessively suppress compensatory mechanisms, and thus may not lead to increased cardiac output and BP. In contrast, ivabradine potentially increases BP and improves BP-limited tolerability of cardioprotective agents in DCM patients with a large and compliant heart. In addition, subsequent titration of cardioprotective agents may provide additional cardiac reverse remodeling.