Authors: Hanan Zaghla M.D, Hatem Al Atroush M.D, Ahmed Samir M.D and Mohamed Kamal M.B.B.Ch.
Background: Patients with chronic obstructive pulmonary disease (COPD) are at special risk of cardiovascular diseases. COPD increases the risk of cardiovascular disease two- to three-fold, Apart from ischemic heart disease, supraventricular and ventricular arrhythmias, as well as conduction disturbances are frequently observed in COPD. Many factors have been implicated as potential triggers of COPD-related arrhythmias with two major hypotheses for arrhythmogenesis have been proposed: arrhythmias may be a consequence of hypoxemia, hypercapnia or acid–base Disturbances since they increase the electrical heterogeneity within the ventricular wall or arrhythmias may be the result of the autonomic neuropathy that characterizes COPD. In the present study, we attempted to non-invasively verify these hypotheses in hypoxemic COPD patients that are not in respiratory failure by examining how PaO2, PaCO2, pH and HCO3correlate with QTd in those patients. Subjects and Methods: In randomized controlled trial, 25 pts with chronic obstructive pulmonary disease underwent: Full history, clinical examination and laboratory investigation. Standard 12-leads and holter electrocardiogram (ECG) for arrhythmia detection and measurement of QT Intervals, Chest X ray (posteroanterior view), two dimensional echocardiography with measurement of LVEDD, LVESD, EF and pulmonary pressure parameters, and myocardial nuclear imaging to exclude ischemic heart disease. Results: We found negative significant correlation between O2 tension and the occurrence of fatal arrhythmias where P value was <0.0005; the same as between O2 tension and QTd value; where P value were <0.0005 in both. *In multiple regression analyses, with QTd as the dependent variable, and age, pulmonary pressure, duration, Mg, Na, K, Hb, PH, CO2 and O2 tensions as the independent variables in all subjects, it was shown that only PaO2 was the predictor of QTd with P value 0.02.* In stable COPD patients enrolled in our study, new cutoff levels for predicting arrhythmic fatality were proposed for QTc parameter ( 395 ms with a sensitivity of 92% and specificity of 83% ) and QTd parameter (58 ms with a sensitivity of 100% and specificity of 92% ).* There is a high positive significant correlation between the age of patients, duration of COPD and Hb level and the occurrence of fatal arrhythmias where P value were 0.009, <0.0005 and <0.0005 respectively; the same as with QTd value where P value were 0.015, 0.001 and 0.039. * There is a positive significant correlation between pulmonary pr. and QTc where P value was 0.041 and pulmonary pr. with QTd where P value was 0.028.Conclusion: Our results rule out the electropathy hypothesis and underline autonomic neuropathy as the most possible mechanism of arrhythmias in hypoxemic, non-respiratory failure, COPD patients. Keywords: COPD, arrhthymia, electropathy, QT interval