Heart Rate Variability-Guided Exercise Training Compared With Standard Exercise Training in Patients With Coronary Artery Disease: A Randomized Clinical Trial

PURPOSE: This study aimed to compare heart rate variability-guided (HRV-G) exercise training versus standard exercise training (SET) on peak oxygen uptake (V̇O₂ peak ) in patients experiencing an acute coronary syndrome event. METHODS: This randomized controlled trial included 48 patients randomized to HRV-G or SET. Both groups consisted of 3 aerobic exercise sessions per week for 3 months. For the HRV-G group, daily exercise was based on a 5-minute morning heart rate recording and the root mean square of successive differences between normal heartbeats (RMSSD). If RMSSD was within ±0.5 SD from baseline, a high-intensity interval training session was performed; if beyond ±0.5 SD , an active recovery session was prescribed. The SET group did 2 sessions of moderate-intensity continuous exercise and 1 session of high-intensity interval training per week, irrespective of HRV status. RESULTS: The V̇O₂ peak increased significantly in both groups (+1.9 mL·kg -1 ·min -1 , P = .002 for SET and +2.1 mL·kg -1 ·min -1 , P < .001 for HRV-G) with no significant group-by-time interaction ( P = .794). Fifty percent of patients were considered responders (ΔV̇O₂ peak change post-pre >5%) in the SET group versus 75% in the HRV-G group ( P = .111). There was a significant time-by-group interaction for V̇O 2 at the first ventilatory threshold, adjusted for lean body mass, showing greater improvement in the HRV-G group compared with the SET group ( P = .043). The training load was significantly lower in HRV-G. CONCLUSIONS: In patients with coronary artery disease, HRV-G exercise training led to similar V̇O₂ peak improvements and prevalence of responders but a larger improvement in V̇O 2 at the first ventilatory threshold adjusted for lean body mass compared with SET, despite a lower training load.