Severity of Cardiovascular Autonomic Neuropathy Is a Predictor Associated With Major Adverse Cardiovascular Events in Adults With Type 2 Diabetes Mellitus: A 6-Year Follow-up Study

Objectives: Cardiovascular autonomic function impairment has been reported in patients with type 2 diabetes mellitus and is associated with cardiovascular events. In this study, we test the hypothesis that the severity of cardiovascular autonomic neuropathy is a predictor associated with subsequent 3-point major adverse cardiovascular events (3-P MACE; combined endpoint of cardiovascular death, nonfatal myocardial infarction and nonfatal stroke). Methods: In this prospective study, we enrolled 168 patients with type 2 diabetes mellitus over a 6-year follow-up period. We constructed the Composite Autonomic Scoring Scale as a measure of the severity of cardiovascular autonomic neuropathy and examined baseline clinical and laboratory data of 168 patients with diabetes. Cardiovascular autonomic testing included heart rate response to deep breathing, Valsalva ratio and baroreflex sensitivity. Therapeutic outcome was defined as 3-P MACE. Results: The overall incidence of new 3-P MACE was 23.2% and overall fatality rate was 9.5% during the 6-year follow-up period. Only underlying coronary heart disease and Composite Autonomic Scoring Scale were independently associated with subsequent 3-P MACE in the Cox proportional hazards model. Any increase of 1 point in Composite Autonomic Scoring Scale would increase the risk of new 3-P MACE by 9.7%. Area under the curve on receiver-operating characteristic curve analysis was 0.72 in predicting subsequent 3-point MACE in combined heart rate response to deep breathing and Valsalva ratio. Conclusions: Besides underlying coronary heart disease, the severity of cardiovascular autonomic neuropathy is strongly associated with subsequent 3-P MACE. Combined heart rate response to deep breathing and Valsalva ratio testing can increase sensitivity and specificity in predicting subsequent 3-point MACE, and it can serve as a time-effective cardiovascular autonomic screening service in the outpatient clinic sitting.