Few HF patients likely to be suitable for ivabradine
MedWire News: The number of heart failure (HF) patients suitable for ivabradine therapy is likely to be small, report UK researchers.
According to national and international guidelines, the decision to add ivabradine should be made after allowing adequate time to uptitrate conventional medical therapy, say Andrew Clark and co-authors from the University of Hull. Their research suggests this would be relevant in only a small proportion of patients.
SHIFT (Systolic Heart Failure treatment with If inhibitor ivabradine Trial) suggested that ivabradine was beneficial when added to a beta blocker in heart failure patients who were in sinus rhythm, whose resting heart rates remained at 70 beats per minute, and who had worse than moderate left ventricular impairment.
Clark et al decided to quantify the proportion of patients eligible for ivabradine therapy. They studied 2211 patients who had significant left ventricular systolic dysfunction (left ventricular ejection fraction [LVEF] ≤50%) and were referred to a community heart failure clinic between 2000 and 2010 for assessment of potential HF. Patients were followed-up at baseline, and after 4 and 12 months.
The results demonstrated that the proportion of patients who fitted the SHIFT profile for benefiting from ivabradine therapy (defined as LVEF of 35% or less, sinus rhythm, and a resting heart rate of 70 beats per minute) fell from 19.4% (n=429) at baseline, to 14.1% (n=185) at 4 months, and 9.3% (n=82) at 12 months.
The proportion of patients suitable for ivabradine therapy at 12 months fell further still, to 5.3% (n=48), when patients with New York Heart Association class I symptoms and/or no beta blocker therapy were excluded from the analysis.
At 12 months, ivabradine-suitable patients had symptomatically worse HF, lower systolic blood pressure, wider QRS duration, and worse left ventricular function than unsuitable patients. In addition, they were prescribed lower doses of beta blocker. This may be at least in part due to intolerability, although intolerance of beta-blocker therapy is often exaggerated to the detriment of the patient, the researchers note in the journal Heart.
They conclude: "Ivabradine reduces the risk for patients with moderate left ventricular systolic impairment who remain in sinus rhythm and have a high resting heart rate, but the proportion of such patients in a specialist heart failure clinic is only small."
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By Piriya Mahendra