PM031 Carotid intima media thickness is associated with reduced heart rate recovery time in patients with low cardiovascular risk profile

Abstract

O ST E R A B ST R A C T S Introduction: The chronotropic response to exercise and the heart rate recovery (HRR) following exercise are non-invasive measures of autonomic function, which are easily measured duringmaximal exercise stress testing. Bothmeasures are independent predictors of sudden cardiac death. Abnormal ventricular repolarization, evidenced clinically by corrected QT interval (QTc) prolongation, may represent the mechanism leading to fatal sequelae. Objectives: The current study aimed to delineate relationships between the resting and post-exercise QTc with the HRR and chronotropic response during treadmill exercise stress testing. The study compared these associations in patients with and without diabetes. Methods: Data of 95 patients (34 with diabetes; mean age 61 years) referred for exercise stress testing were analysed retrospectively for QTc interval, chronotropic response and HRR. The QT interval was measured at rest and 30, 120, 210 and 300 s post-exercise, and was rate corrected using the Bazett, Fridericia, Framingham and Hodges formulae. No patients had evidence of cardiac ischaemia. Results: Significant inverse relationships were found between (1) resting Hodges QTc interval and HRR; (2) post-exercise QTc intervals and HRR at 30, 120, 210 and 300 s; and (3) resting and post-exercise QTc intervals and chronotropic index. Multivariate regression analysis using the entire patient group identified an independent association between the Bazett QTc interval 120 s and HRR 120 s (r1⁄4-0.40, p<0.001). Diabetic patients showed significantly lengthened QTc intervals at rest and post-exercise and both attenuated chronotropic response and HRR compared to the control group. The strength of associations between the QTc, HRR and chronotropic response were similar in patients with and without diabetes. Conclusion: The findings suggest abnormal ventricular repolarisation may be a mechanistic link by which blunting of the heart rate recovery and chronotropic response are related to sudden cardiac death. The inclusion of these non-invasive autonomic measures in routine exercise stress testing may provide additional risk stratification. Disclosure of Interest: None Declared