Delayed heart rate recovery after exercise foretells MetS development

Delays in the slow phase of heart rate recovery (HRR) may be an early indicator for the risk of developing metabolic syndrome (MetS), a new study has found.

The researchers conducted a retrospective longitudinal cohort analysis of 2,167 participants (mean age 52.2±6.4 years, 84.0 percent men) with HRR measurements available for analysis. HRR was calculated as the peak heart rate minus the resting heart rate after a 1- (HRR1), 2- (HRR2), and 3-minute (HRR3) resting period. The outcome was the development of MetS defined according to the Joint Interim Statement of the International Diabetes Federation Task Force on Epidemiology and Prevention.

Over 9,683 person-years of follow-up, MetS occurred in 31.2 percent (n=676) of participants. HRR3 was significantly lower in these participants than in those who did not develop MetS (56.1±11.4 vs 58.3±11.3 bpm; p<0.001). There were no differences in HRR1 and HRR2.

After grouping participants into tertiles of HRR3, Cox proportional hazards analysis showed that the risk of MetS was significantly elevated in the bottom (hazard ratio [HR], 1.492, 95 percent confidence interval [CI], 1.146–1.943) and second (HR, 1.277, 95 percent CI, 1.004–1.624) tertiles relative to the topmost group.

The interaction between HRR3 and MetS risk remained significant even when taking HRR3 as a continuous variable. Each 1-beat decrease in HRR3 correlated with a 1.5-percent increase in MetS risk (HR, 1.015, 95 percent CI, 1.005–1.026). No such effects were reported for HRR1 and HRR2.

“The important findings of this study were that delayed HRR following a graded exercise treadmill test was an independent predictor of MetS development, and that HRR3 was a potent predictor of incident MetS,” the researcher said.