The association between insulin resistance (IR) and heart rate recovery index (HRRI) has been reported previously, but the cardiovascular disease (CVD) risk profile of the subjects was unclear in these studies. Therefore, we evaluated the association between IR and HRRI in apparently healthy individuals without metabolic syndrome who had a low-to-moderate CVD risk profile. A total of 182 eligible subjects were retrospectively included in the study. The subjects were divided into two groups according to the homeostasis model assessment of IR (HOMA-IR) value. HOMA-IR ≥2.5 was defined as IR (+) group (92 subjects), and <2.5 as IR (-) group (88 subjects). HRRI-2 was found by subtracting the heart rate at the second minute in the post-exercise recovery period from the maximum heart rate. Abnormal HRRI was defined as HRRI-2 that is ≤42 beats. The mean age of the patients was 41.91 ± 8.64 and 49.4% of them were female. Abnormal HRRI rates were significantly higher in the IR (+) group (37.2% vs 18.2%; p = 0.004). A negative correlation was detected between HRRI-2 and HOMA-IR (r = -0.416; p < 0.001). HOMA-IR (Odds Ratio (OR) = 1.57; confidence interval (CI) = 1.10-2.23; p = 0.013) and maximum heart rate during exercise (OR = 0.95; CI = 0.91-0.99; p = 0.013) as independent variables of abnormal HRRI. The HOMA-IR value of 2.82 was identified as an effective cutoff point for the prediction of abnormal HRRI (area under the curve: 0.658; CI: 0.570-0.746; p = 0.001). In this study, it was shown that IR without metabolic syndrome reduces HRRI in healthy individuals with a low-to-moderate CVD risk profile.
Keywords: Cardiovascular disease; heart conduction system; insulin resistance.