Electrocardiographic features in patients with Diabetes Mellitus who are Asymptomatic for Cardiac Disease and utility of poor R wave progression in predicting cardiac function

BACKGROUND: Diabetes mellitus is an important metabolic disorder that can affect nearly every organ system in the body. In India, it is estimated that the prevalence of diabetes is likely to go up to 57.2 million by the year 2025. Cardiac dysfunction and silent MI are major life threatening complications in diabetes so we aim to determine the electrocardiographic features in patients with asymptomatic diabetes mellitus and determine the utility of poor R wave progression in predicting cardiac function. OBJECTIVES: To determine the electrocardiographic features in patients with diabetes mellitus who are asymptomatic for cardiac disease and to determine the utility of poor R wave progression in predicting cardiac function. DESIGN: Prospective observational study. SETTING: General Medicine and Diabetic OPD at Christian Medical College, Hospital Vellore. PATIENTS: 125 diabetics who are asymptomatic for cardiac disease and fulfilled the inclusion criteria. METHODS: This was a prospective observational study which was done between June 2018 and June 2019. Once patients were identified, they were given the Information sheet, following which written informed consent was obtained. All study data were collected by the principal investigator. The participants of the study or their bystanders were interviewed and data were collected. Demographic data including age, sex, occupation, and BMI were obtained. The ECG was performed for all the participants, the ECG features and parameters such as gender, age, coexistent micro- macro vascular complications and duration of type 1 and 2 diabetes mellitus was analysed. An Echocardiography for patient with poor R wave progression was done to look for cardiac function by ejection fraction and it was compared with the participants without poor R wave progression of similar baseline characterstics. RESULTS: In this study 19.2% of the diabetics who were asymptomatic for cardiac disease had normal ECG and 80.8% had ECG changes. The most common ECG changes were – Resting sinus tachycardia – 6.4%, Left ventricular hypertrophy – 13.6%, Left atrial enlargement – 5.6%, ST-T changes – 12%, QTc prolongation or QTc dispersion – 11.2% and Poor R wave progression (PRWP)– 13.6%. PRWP was seen in 13.6% of asymptomatic diabetics. The duration of diabetes was more in patients with PRWP- Mean - 10.82 years than with no PRWP- Mean- 8.25 years. The difference among the means were 3.73 with 95% confidence interval difference of the difference being 1.47 – 5.89, p- value was 0.006. Hence, in our study the duration of diabetes was an independent predictor of the PRWP in asymptomatic diabetics. 11 out of 17- 64.7% of the patients with diabetic neuropathy had PRWP, with the relative risk of 2.75, p- value of 0.027. Hence, diabetic neuropathy was an independent predictor of PRWP in diabetics asymptomatic diabetics. Also 7 (41.17%) out of 17 patients who had PRWP on ECG had heart failure on the 2-D ECHO, p-value - 0.015. Hence, PRWP was an independent predictor of heart failure in diabetics asymptomatic diabetics and showed a strong association. CONCLUSION: Diabetes mellitus is a disease with significant mobidity and mortality because of the underlying microvascular and macrovascular complications. But appropriate early screening and diagnostic tests can prevent the progression of the complications. 12-lead Electrocardiogram is an important tool in both diagnostic and the researcher pursuit as a detection and screening tool of myocardial injury. Certain ECG features like sinus tachycardia, LVH, LAD, QTc prolongation, ST-T changes, Left atrial enlargement and PRWP can be seen in diabetics asymptomatic for cardiac disease which appear early in the ongoing pathology of the myocardial injury. Duration of diabetes and diabetic neuropathy are an independent predictor of PRWP on ECG in diabetics asymptomatic for cardiac disease. PRWP is independent predictor of heart failure in diabetics asymptomatic for cardiac disease