Chronotropic incompetence predicts impaired response to exercise training in heart failure patients with sinus rhythm.

Background: In most patients with chronic heart failure (CHF), endurance training improves exercise capacity. However, some patients do not respond favourably. The purpose of this study was to explore the reasons of non-response and to determine their predictive value.

Methods: We studied a cohort of 120 consecutive CHF patients with sinus rhythm (mean age 57 ± 12 years, ejection fraction 29.3 ± 9.9%, peak VO₂ 17.3 ± 5.1 ml/min/kg), participating in a 3-month outpatient cardiac rehabilitation programme. Responders were defined as subjects who improved peak VO₂ by more than 5%, work load by more than 10%, or VE/VCO₂ slope by more than 5%. Subjects who did not fulfil at least one of the above criteria were characterized as non-responders. Multivariate regression analyses were performed to identify parameters that were predictive for a response. Receiver operating characteristic (ROC) analyses were performed for predictive parameters to identify thresholds for response or non-response.

Results: Multivariate regression analyses revealed heart rate (HR) reserve, HR recovery at 1 min, and peak HR as significant predictors for a positive training response. ROC curves revealed the optimal thresholds separating responders from non-responders at less than 30 bpm for HR reserve, less than 6 bpm for HR recovery and less than 101 bpm for peak HR.

Conclusions: The presence of impaired chronotropic competence is a major predictor of poor training response in CHF patients with sinus rhythm.