METHODS
The patients, who were recently diagnosed with COPD in the Chest
Diseases Outpatient Clinics of the Harran University Faculty of
Medicine, were enrolled in the study. The exclusion criteria consisted
of the presence of diabetes mellitus, hypertension, chronic or acute
heart failure, moderate or severe valvular heart disease,
hyperthyroidism, anemia, sleep disorders, ECG signs of incomplete or
complete bundle branch block. The local ethics committee approved the
study, which was conducted in full compliance with the Declaration of
Helsinki. The signed informed consent were obtained from all patients.
Tests for Pulmonary Function and Diffusing Capacity of the Lung Carbon
Monoxide (DLCO) as recommended by the American Thoracic Society (ATS)
were performed in all patients 12. The assessment of
pulmonary function was performed with at least three forced expiratory
maneuvers in 90° upright position with the nose closed, and the best
value was recorded. The measurements of Forced Vital Capacity (FVC),
Forced Expiratory Volume in 1 second (FEV1), and the ratio of FEV1 / FVC
were recorded. The current guideline was used for COPD diagnosing and
staging [1]. Accordingly, a post-bronchodilator FEV1 / FVC
< 70% in the presence of clinical findings indicates
persistent airflow limitation and is essential for diagnosing COPD. The
GOLD (Global Obstructive Lung Disease ) stage of COPD is categorized as
stage 1 (mild) when post-bronchodilator predicted FEV1 is equal to or
greater than 80%, stage 2 (moderate) when between 50% and less than
80%, stage 3 (severe) when between 30% and less than 50%, and stage 4
(very severe) when less than 30%. Accordingly, the current study
population was categorized into two groups as Group I, including the
mild and moderate COPD patients, and Group II, including the severe and
very severe COPD patients. The single-breath method via the Morgan
Benchmark transfer test was used for the quantification of DLCO.
A 12-lead basal ECG with a 0.16–100 Hz filter range, 25 mm/s speed, and
10 mm/mV height both at rest and in the supine position was obtained
from all patients on admission. The automatically reported axes of QRS
and T wave were used to calculate the frontal QRS-T angle by using the
formula: Frontal QRS-T angle = │QRS axis – T axis│. When the angle was
greater than 180o, its subtraction from
360o was used for the calculation, as previously
reported 13. Figure 1 depicts an example of the
frontal QRS-T angle calculated as explained.
Blood samples for laboratory tests, including complete blood count and
biochemical parameters consisting of serum electrolytes, liver enzymes,
urea, and creatinine, were obtained from all patients on admission.