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A4989 - Effects of Airway Obstruction and Hyperinflation on Electrocardiographic Axes in COPD
Author Block: P. Alter1, H. Watz2, K. Kahnert3, K. F. Rabe4, F. Biertz5, R. Fischer5, P. Jung6, J. Graf7, R. Bals8, C. F. Vogelmeier1, R. A. Jörres7; 1Department of Medicine, Pulmonary and Critical Care Medicine, Philipps University of Marburg, Marburg, Germany, 2Pulmonary Research Institute at LungenClinic Grosshansdorf, Airway Research Centre North (ARCN), Grosshansdorf, Germany, 3Department of Internal Medicine V, University of Munich (LMU), Comprehensive Pneumology Center, Member of the German Center for Lung Research, Munich, Germany, 4Department of Internal Medicine, LungenClinic Grosshansdorf and Christian-Albrechts University, Kiel, Airway Research Centre North (ARCN), Grosshansdorf, Germany, 5Institute for Biostatistics, Centre for Biometry, Medical Informatics and Medical Technology, Hannover Medical School, Hannover, Germany, 6Internal Medicine, Dachau, Germany, 7Institute and Outpatient Clinic for Occupational, Social and Environmental Medicine, Ludwig Maximilians University, Munich, Germany, 8Internal Medicine V - Pulmonology, Saarland University Hopsital, Homburg, Germany.
Rationale. Influences of the lung disorder on the heart have been repeatedly shown in COPD, including effects on the left ventricle (LV) and the electrocardiographic axes of the heart. It is yet not known to which extent these alterations are due to changes in lung function parameters. We therefore quantified the relationship between airway obstruction, lung hyperinflation and the orientation of the electrical P wave, QRS and T wave axis based on the surface electrocardiogram (ECG) in patients with COPD.
Methods. Data from the baseline visit of the COPD cohort COSYCONET were analyzed, using forced expiratory volume in 1 second (FEV1), intrathoracic gas volume (ITGV), left ventricular (LV) mass from echocardiography, as well as ECG data including the P wave, QRS and T wave axis. Data were analyzed by multiple regression analyses and structural equation modeling (SEM).
Results. Data from 1195 patients fulfilled the inclusion criteria (mean±SD age: 63.9 ± 8.4 years; GOLD 0-4: n=175/107/468/363/82). The orientations of P wave, QRS and T wave axes differed significantly from each other (mean±SD: 60.5° ± 25.0°, 36.1° ± 42.6°, 53.3° ± 23.1°, respectively). The three ECG axes were significantly associated with the degree of airway obstruction (FEV1) and hyperinflation (ITGV). The QRS axes according to GOLD grades 0-4 were (mean±SD): 26.2° ± 37.5°, 27.0° ± 37.7°, 31.7° ± 42.5°, 46.6° ± 42.2°, 47.4° ± 49.4°. Effects of lung function resulted in an incremental clockwise rotation of the axes by 25° to 30° in COPD patients with severe airway disease. The most frequent measured type was a vertical one; when subtracting out pulmonary influences, this changed to a normal one. There were additional associations with BMI, diastolic blood pressure, the RR interval, QT duration and LV mass as revealed by regression analysis. Their direct and indirect effects on the orientation of the axes was comprehensively analyzed and quantified using SEM.
Conclusion. Significant clockwise rotations of the electrical axes as a function of airway obstruction and lung hyperinflation in COPD were shown. The changes are likely to result from both a change of the anatomical orientation of the heart within the thoracic cavity and a reduced LV mass in COPD. The influences on the electrical axes reach an extent that could lead to misinterpretation of the ECG in severe COPD. The magnitude of lung function impairment should be taken into account to uncover other cardiac disease and to prevent misdiagnosis.