Cardiac autonomic function and insulin resistance for the development of hypertension: a six-year epidemiological follow-up study.

ABSTRACT

BACKGROUND AND AIMS: To explore the impact of cardiac autonomic function (CAF) and insulin resistance (IR) on incident hypertension. METHODS AND RESULTS: In 1996, 1638 subjects finished baseline examination, which included anthropometry, blood pressures, CAF, blood biochemistry, plasma insulin, urine examination and electrocardiogram. CAF included standard deviation of normal-to-normal intervals or RR intervals (SDNN), low- and high-frequency power spectrum (LF and HF), and LF/HF ratio at supine for 5 min, the RR interval changes during lying-to-standing maneuver, and the ratio between the longest RR interval during expiration and the shortest RR interval during inspiration (E/I ratio). We used homeostasis model assessment to define beta cell function (HOMA-B) and insulin resistance (HOMA-IR). In total, 992 non-hypertensive participants completed the follow-up assessment in 2003 and 959 participants were included for the final analysis. Incident hypertension was determined by blood pressure status at follow-up. In unadjusted model, both square root of HOMA-IR (OR3.37, 95%CI 2.10-6.64) and HOMA-B (OR0.996, 95%CI 0.992-0.999) were related to incident hypertension. In multivariate model, square root of HOMA-IR (OR1.97, 95%CI 1.05-3.70), but not HOMA-B, was associated with incident hypertension. After further adjustment for baseline CAF, the positive relationship between the square root of HOMA-IR and incident hypertension disappeared. In contrast, LF/HF ratio (OR1.18, 95%CI 1.01-1.37), HF power (OR0.98, 95%CI 0.96-0.999), and E/I ratio (OR0.71, 95%CI 0.54-0.95) were each independently associated with incident hypertension after further adjustment for HOMA measures. CONCLUSION: Sympathovagal imbalance with an apparently decreased parasympathetic tone is an important predictor of incident hypertension independent of IR.