Obesity, Cardiac Autonomic Dysfunction and QTc Prolongation in Patients with Myocardial Infarction: A Cross-Sectional Comparison with Healthy Controls
DOI:
https://doi.org/10.69980/ajpr.v29i1.959Keywords:
Obesity, Myocardial infarction, Heart rate variability, RMSSD, QTc interval, Dyslipidaemia, Autonomic dysfunctionAbstract
Background: Low vagal tone and a long QTc interval both raise the risk of arrhythmia and death after myocardial infarction (MI). Obesity may worsen both. This study compared heart rate variability (HRV), lipid profile, HbA1c and QTc among obese MI patients, non-obese MI patients and healthy controls, and tested whether BMI independently predicts low vagal HRV.
Methods: This cross-sectional study at Index Medical College, Malwanchal University, Indore included 100 obese MI patients (BMI ≥ 25 kg/m²), 100 non-obese MI patients (BMI 18.5–22.9 kg/m²) and 100 healthy controls, aged 35–65 years. HRV (SDNN, RMSSD, LF/HF ratio), fasting lipids, HbA1c, Troponin T, CK-MB and QTc were measured. ANOVA with Tukey's test, chi-square test, Pearson's correlation and multiple linear regression were used.
Results: RMSSD was 17.5 ± 4.9 ms in obese MI patients, 51.0 ± 11.1 ms in non-obese MI patients and 37.6 ± 7.6 ms in controls (p < 0.001). RMSSD was below 19 ms in 52% of obese MI patients and in none of the others. Low HDL was present in 96% of obese vs 28% of non-obese MI patients, and QTc prolongation in 13% vs 1% (p = 0.001). Among MI patients, RMSSD correlated negatively with BMI (r = −0.81), triglycerides (r = −0.83) and QTc (r = −0.59). On regression, BMI (β = −0.30), triglycerides (β = −0.46) and LDL (β = −0.28) independently predicted lower RMSSD (all p < 0.001; adjusted R² = 0.76).
Conclusion: Obese MI patients have a marked loss of vagal tone, a poor lipid profile and more frequent QTc prolongation. BMI and triglycerides independently predict low RMSSD. Obese MI patients should be screened with simple HRV and ECG measures.
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