Exercise heart rate gradient: a novel index to predict all-cause mortality

Area of Science:

• Cardiology
• Exercise Physiology
• Preventive Medicine

Background:

• Reduced exercise heart rate (HR) reserve and recovery are linked to increased all-cause mortality risk.
• A combined index for these variables has not been previously explored.

Purpose of the Study:

• To create a novel index, the Exercise Heart Rate Gradient (EHRG), by combining HR reserve and recovery.
• To evaluate the EHRG's utility in predicting all-cause mortality.

Main Methods:

• Retrospective cohort analysis of 1476 participants (aged 41-79).
• Maximal cycle cardiopulmonary exercise tests were performed.
• HR reserve and recovery were calculated, divided into quintiles, and summed to create the EHRG score (2-10).
• Survival analyses compared EHRG scores and lowest quintiles (Q1) of HR reserve and recovery for mortality prediction.

Main Results:

• During a mean 7.3-year follow-up, 44 deaths occurred (3.1%).
• A lower EHRG score correlated with a higher death rate (p < 0.05).
• An EHRG score of 2 was a superior predictor of all-cause mortality compared to Q1 HR reserve or Q1 HR recovery alone (age-adjusted hazard ratios: 3.53 vs. 2.52 and 2.57).

Conclusions:

• The Exercise Heart Rate Gradient (EHRG) is a novel index combining HR reserve and recovery.
• EHRG demonstrates superior predictive capability for all-cause mortality risk compared to individual measures of HR reserve or recovery.