Relationship of the ECG with ventilatory function tests in chronic obstructive lung disease (COLD) in Nigerians

Although the most objective assessment of the severity of COLD is done by spirometer, this is not as readily available in Nigeria as the electrocardiograph, thus the ECG is often used to assess it. This study examines the relationship between the ECG findings and FEV 1 obtained by spirometry and expressed as a proportion predicted for age and sex in 92 Nigerians with COLD of which 39 had associated pulmonate. There was an inverse relationship between the mean electrical axis of the P wave on the ECG and the FEV 1 of predicted. The axis was more positive (82 +/- 12 degrees) among those with FEV 1 less than 50% of predicted (group 1) and this decreased progressively with increasing FEV 1 to 72 +/- 14 degrees in those with FEV 1 between 50-70% (group 2) and 67 +/- 16 degrees in those with FEV 1 greater than 70% (group 3). There was also a significant relationship between FEV 1 and the development of cor pulmonale and 71.4% of those who had the lowest FEV 1 (group 1) had cor pulmonale while the proportion decreased with the reduction in the severity of airway obstruction. A rightward P wave axis greater than 80% was statistically significant associated with development of cor pulmonale (X2 = 29.5 (P < 0.001) of those with COLD and cor pulmonale, 72.2% had a P wave axis greater than 80%. Only 13.2% of those with COLD alone had a P wave axis greater than 80 degrees. Cardiac arrhythmias were present in 28 patients, ventricular (VA) in 23 cases, and atrial (AA) in 7 cases. Both AA and VA were associated with more severe airway obstruction. All 3 patients who had atrial fibrillation (AF) and FEV 1 below 50% of predicted (group 1) and had cor pulmonale while 2 of the remaining 4 with AA also were in group 1 and the remaining 2 in group 2. The distribution of ventricular arrhythmias (VA) showed that 10 (43.5%) were in group 1, 9 (39.1%) in group 2, and 2 (8.7%) in group 3. Both VA and AA were also significantly related to the development of cor pulmonale. A P wave amplitude greater than 2.5 mm was significantly related to the development of clinical cor pulmonale X2 = 24.6 P < 0.001. The results show that ECG findings correlate well with spirometric assessments of FEV 1 and clinical severity in Nigerians with COLD and are, therefore, useful where spirometry is unavailable.