Objective: To study the temporal relationship of smoking with electrophysiological changes.
Design: Prospective observational study.
Setting: Tertiary cardiac center.
Participants: Male smokers with atypical chest pain were screened with a treadmill exercise test (TMT). A total of 31 such patients aged 49.8±10.5 years, in whom TMT was either negative or mildly positive were included. Heart rate variability (HRV) parameters of smokers were compared to those of 15 healthy non-smoking participants.
Interventions: All patients underwent a 24 h Holter monitoring to assess ECG changes during smoking periods.
Results: Heart rate increased acutely during smoking. Mean heart rate increased from 83.8±13.7 bpm 10 min before smoking, to 90.5±16.4 bpm during smoking, (p<0.0001) and returned to baseline after 30 min. Smoking was also associated with increased ectopic beats (mean of 5.3/h prior to smoking to 9.8/h during smoking to 11.3/h during the hour after smoking; p<0.001). Three patients (9.7%) had significant ST-T changes after smoking. HRV index significantly decreased in smokers (15.2±5.3) as compared to non-smoking controls participants (19.4±3.6; p=0.02), but the other spectral HRV parameters were comparable.
Conclusions: Heart rate and ectopic beats increase acutely following smoking. Ischaemic ST-T changes were also detected during smoking. Spectral parameters of HRV analysis of smokers remained in normal limits, but more importantly geometrical parameter-HRV index-showed significant abnormality.