Aims: 

Chronic myocardial infarction (CMI) is associated with electrical instability. Obesity increases ventricular variability indices and the incidence of abnormal signal averaged electrocardiograms (SAECG). The aim of this study was to assess the influence of obesity on electrical instability in CMI patients.

Methods: 

32 chronic myocardial infarction patients, 14 obese (body mass index-BMI: 33 ± 3 kg/m²) and 18 normal weighted (BMI: 26 ± 2 kg/m²), underwent SAECG (to detect late ventricular potentials-LVP) and 12-lead ECG (assessing ventricular activity variability indices: QT and QRS dispersion, as the differences between maximal and minimal duration of the ECG intervals).

Results: 

QRSdc (heart rate corrected QRS dispersion) was 32 ± 27 ms in obese, and 17 ± 12 ms in normal weighted CMI patients. QTdc (heart rate corrected QT dispersion) was 35 ± 23 ms in obese and 33 ± 25 ms in the normal weighted group. SAECG parameters were: SA-QRS (SAECG QRS duration): 127 ± 28 ms, LAS40 (Low Amplitude Signal): 61 ± 40 ms and RMS40 (Root Mean Square): 20 ± 14mV. QRSdc correlated with BMI (r = 0.604) and was significantly increased in obese (32 ± 27 ms) compared to normal weighted CMI patients (17 ± 12 ms) (p = 0.0027). The mean values for QTdc were higher in the obese (28.4 ms) compared to the normal weighted patients (26.75). Late ventricular potentials were present in 71% of the obese patients and 56% of the normal weighted CMI patients. SAECG parameters also correlated with BMI: r (SA-QRS, BMI): 0.5, r(LAS40, BMI):0.45.

Conclusion: 

The presence of obesity in CMI affects intraventricular conduction, increasing ventricular arrhythmia risk. There exists a BMI associated increase in CMI patients' sudden death risk.