Heart rate deceleration after exercise predicts patients most likely to respond to cardiac resynchronisation therapy

This study examines the relationship between heart rate recovery following exercise and subsequent response to cardiac resynchronisation therapy (CRT).

Blunted heart rate recovery is an adverse prognostic marker in heart failure and has been shown to correlate with disease severity.

37 patients receiving biventricular pacemakers for conventional indications underwent functional assessments; cardiopulmonary exercise test, 6-min walk test and quality-of-life assessment, together with echo analyses, before and at 3 months following implant. Heart rate deceleration (HRD) gradients were calculated at 30-, 60-, 90- and 120-s intervals following cessation of the baseline exercise test and compared with subsequent markers of response to CRT. Functional response was defined as > or =20% improvement in any two of the three functional assessments, and echo response defined as > or =5% increase in ejection fraction.

Functional responders demonstrated steeper HRD gradients than non-responders at 30, 60 and 90 s. Echo responders also demonstrated steeper HRD at 30 and 60 s from the cessation of exercise. Receiver-operating curve analysis demonstrates area under the curve of 0.87 and 0.82, respectively, for HRD30 to predict functional and echo response to CRT. A cut-off value of 3 for HRD30, equating to a 5% reduction in HR between peak exercise and 30 s into recovery, demonstrates the optimal sensitivity/specificity profile to perform this function.

HRD following exercise correlates with functional and echocardiographic response to CRT. Application of this parameter in addition to standard criteria may provide valuable supplementary information in the evaluation of prospective CRT candidates.