Acute electrocardiographic changes during smoking and tobacco chewing: A Cross-sectional study

Background: Smoking increases the risk of coronary artery disease. Very few studies have evaluated the temporal relationship of electrocardiographic changes with smoking. We sought to study and compare the electrocardiogram (ECG) changes during smoking and tobacco chewing in current smokers and tobacco chewers presenting with atypical chest pain with either negative or mild positive exercise ECG test (treadmill test [TMT]). Materials and Methods: We screened male smokers and tobacco chewers with atypical chest pain with TMT. A total of 60 patients, 30 in each group in whom TMT was either negative or mildly positive, underwent a 24-h Holter monitoring. We asked patients to note down their time of smoking and tobacco chewing along with the timing of symptoms if any. Results: All patients were male with an average age of 45 years in smokers and 42 years in the tobacco chewer group. The mean number of cigarettes consumed was 6 ± 2.8 and tobacco chewed was 5 ± 4.7 g/day. Heart rate (HR) in smokers increased from 82.5 ± 14.56/min 10 min before smoking to 90.63 ± 15.34/min, during smoking with peak HR achieved at the time of smoking (P < 0.0001). HR in the tobacco chewers peaked at 10 min after chewing from 80.62 ± 13.52/min 10 min before to 87.89 ± 13.86/min 10 min after chewing (P < 0.0001). Smoking was associated with a significant increase in supraventricular ectopics (VEs) from 3.98/h before smoking to 7.43/h during and 6.92/h after smoking (P < 0.0001). Two patients in the smoker subgroup had spontaneous smokeless tobacco -T changes lasting for 10–25 min. Smoking was associated with a significant decrease in HR variability (HRV) index than the controls (P = 0.023). Tobacco chewing was not associated with any significant changes in the HRV parameter. Conclusions: Smoking and tobacco chewing both significantly increase the HR acutely. Smoking leads to an increase in both supraventricular and VEs. We observed reduced HRV in patients who smoked cigarettes.