Photo Credit: Lesia Yavorska
Heart rate variability shows promise as a useful screening tool to predict microvascular and macrovascular complications in patients with type 2 diabetes.
Heart rate variability (HRV) shows promise as a useful screening tool to predict microvascular and macrovascular complications in patients with type 2 diabetes, researchers in India report.
“Diabetes patients with complications have significantly lower HRV than those without complications. A strong correlation between HRV indices and complications of diabetes has been demonstrated,” Leena Phadke, MD, and her coauthors wrote in Journal of The Association of Physicians of India. “This makes HRV a promising prescreening tool to predict micro- and macrovascular complications in type 2 diabetes patients.”
Type 2 diabetes and its vascular complications seriously affect QOL and are burdensome to healthcare systems, the researchers explained. Uncontrolled diabetes can progress to coronary artery disease (CAD), a major complication. Prediction and timely referral for CAD screening are important, but early detection is challenging. Myocardial ischemia is often silent because patients cannot feel pain due to associated cardiac autonomic neuropathy (CAN).
HRV as a Prescreening Tool
Dr. Phadke and colleagues investigated the utility of heart rate variability, a noninvasive marker of cardiac autonomic activity, as a prescreening tool to help predict vascular complications in type 2 diabetes. Between January and June 2017, they enrolled participants aged between 30 and 70 years with T2DM and no known microvascular or macrovascular diabetes complications in their cross-sectional, observational, single-site study.
Patients with a history of thyroid disorder and those taking drugs that affect HRV, including tricyclic antidepressants, beta-blockers, calcium channel blockers, and ACE inhibitors, were excluded, as were people with arrhythmia or incomplete noisy electrocardiogram records or who were unable to complete all the screening tests.
After a 15-minute resting electrocardiogram, the 60 eligible participants completed an exercise stress test and assessments for nephropathy, retinopathy, and peripheral neuropathy. Those with positive stress test results underwent coronary angiography to confirm coronary artery disease. Based on screening test results, 31 participants had T2DM without microvascular or macrovascular complications, and 29 had T2DM with those complications. Of the 29 participants with complications, 13 were diagnosed with CAD.
Significant increases in average heart rate (90.1 vs. 76.7; P=0.0001) and HbA1c (64 mmol/mol [8.4%] vs. 53 mmol/mol [7.5%]; P=0.02), and a significant decrease in SDNN (standard deviation of the NN interval that indicates overall variability) (18.6 vs. 32.6; P=0.0001), low frequency (ms2), (65 vs. 199.1; P=0.0001), and high frequency (ms2) (60.1 vs. 137.3; P=0.001) were found in the group with complications compared to the group without.
The researchers found significantly lower HRV between the groups and a strong association of HRV indices with diabetes complications. They used logistic regression to classify the complicated vs. the noncomplicated groups, and they observed an area under the curve (AUC) of 0.83 and an accuracy of 0.78 with 85% sensitivity and 74% specificity.
They acknowledged limitations of their study, including HRV being measured under highly controlled conditions to minimize its inter- and intraindividual variations, thus limiting the generalizability of the results to real-world settings where HRV measurement conditions may vary widely.
“In the present study . . . . the HRV indices have shown promising potential as a prescreening tool to predict micro- and macrovascular complications in type 2 diabetes, especially with an added advantage of being noninvasive and simple to measure,” the authors wrote.
