Background: Since late Na channel inhibition (ranolazine) improves exercise duration in the stress laboratory among angina patients, we questioned if this benefit would translate to impact step-count during daily life assessed by a "wearable" device.
Methods: We conducted a pilot substudy within a randomized, double-blinded, placebo-controlled, cross-over trial of subjects with angina, non-obstructive coronary artery disease and coronary microvascular dysfunction. Ranolazine was administered (500-1000mg BID for 2 weeks). The outcome of interest was difference in Fitbit Flex daily step-count during weeks 2 of ranolazine or placebo treatment. Other outcomes included angina, quality of life, ischemia, diastolic function.
Results: 30 subjects were analyzed. Overall, late Na channel inhibition reduced daily step-count vs. placebo (5757 +/- 3076 vs. 6593 +/- 3393, p=0.01) and did not improve angina. However, among those with improved angina (SAQ-7 improvement), a direct correlation with increased step-count (0.42, p=0.02) was observed, most due to typical angina (0.57, p=0.05) (Fig).
Conclusions: We report the "first" data set from a wearable monitor to measure step-count in a controlled late Na channel inhibition trial. Our results suggest short-term late Na channel inhibition (ranolazine) does not increase step-count during daily life.