The effect of smoking on QT dispersion and disease severity in chronic obstructive pulmonary disease

Chronic obstructive pulmonary disease is a multisystemic disorder. Lung involvement is predominat, however it causes systemic inflammation resulting in functional and structural changes in other organ systems. The risk of arrhythmias and the incidence of sudden death are increased in patients with chronic obstructive pulmonary disease. QT dispersion is a marker of heterogenous ventricular repolarization and accepted as an independant risk factor for triggering arrhythmias. The aim of our study is to investigate the relationship between QTc and QTcd whith have been accepted as electrocardiographic markers of heterogenous ventricular repolarization and smoking duration, number of the cigarettes smoked, time interval after cessation of smoking in patients with chronic obstructive pulmonary disease who are classified according to GOLD criteria.One hundred patients who were diagonosed as chronic obstructive pulmonary disease according to their medical history, physical examination and pulmonary function tests (GOLD criteria) and 50 healthy control subjects were involved in our study. Fifty of the patients with chronic obstructive pulmonary disease were current smokers and 50 of them were ex-smokers. QTc was calculated using Bazett formula. QT and QTc dispersions were defined as the difference between maximal-minimal QT and QTc values.Group 1 consisted of 44 males (88%) and 6 females (12%), group 2 consisted of 46 males (92%) and 4 females (8%) and group 3 consisted of 41 males (82%) and 9 females (18%). The mean QTcd value was 61,90±21,40 msec in group 1, 47,34±14,56 mec in group 2, 26,84±11,27 msec in group 3We found that QTcd value increased as the stage of chronic obstructive pulmonary disease increased both in smoking and non-smoking patients. Considering the cut-off value of QTcd 60 msec for the risk of ventricular arrhythmias, we determined that QTcd was 60 msec and longer in smokers in stage II and more as well as in ex-smokers in stage IV patients. QTcd value decreased as the time interval increased after cessation of smoking but it was not statistically significant. However a statistically significant increase in QTcd value was observed as the smoking duration and the number of the cigarettes smoked increased. We think that new studies investigating this effect in smoking and non-smoking healthy subjects may contribute to the literature and cessation of smoking in patients with chronic obstructive pulmonary disease may decrease cardiac mortality.