Isosorbide Mononitrate Did Not Up Exercise Tolerance in HF Patients

According to a study presented at the American Heart Association's Scientific Sessions 2015, patients with heart failure with preserved ejection fraction (HFpEF) did not have increased exercise tolerance after taking  isosorbide mononitrate compared to placebo. The findings are also published in the New England Journal of Medicine.

NEAT-HFpEF (Nitrate's Effect on Activity Tolerance in Heart Failure with Preserved Ejection Fraction) was a multicenter, randomized, double-blind, 2-period, 12-week crossover study that examined 110 patients with HFpEF across 20 sites. Patients were randomized to either 6 weeks of placebo first followed by 6 weeks of isosorbide mononitrate or 6 weeks of isosorbide mononitrate followed by 6 weeks of placebo.

The patients' daily activity was measured with accelerometers to asses movement throughout the day. Researchers found that daily activity progressively and significantly decreased as the nitrate dose increased.

During the 120mg dose of isosorbide mononitrate, patients were active for 18 less minutes per day vs. when they received a placebo. Previous studies had demonstrated that adverse outcomes (eg, death, hospitalization) were associated with HF patients with reduced ejection fraction that experienced even 10 fewer minutes of activity per day.

For all doses of isosorbide mononitrate (30–120mg), patients were overall less active daily compared to when they received placebo. The daily accelerometer units decreased on average as the nitrate dose increased but not when patients were given placebo. Isosorbide mononitrate did not improve exercise test (6-minute walk distance) or quality of life scores, noted Margaret Redfield, MD, first author of the study.

She concluded, "The decrease in activity occurred in the absence of adverse effects on six-minute walk distance and in association with directionally adverse, albeit not statistically significant, effects on quality-of-life scores. These findings suggest that activity levels were sensitive to subtle adverse effects of isosorbide mononitrate."

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