Electrocardiographic signs of cardiac ischemia at rest and during exercise in patients with COPD travelling to 3100 m. Data from a randomized trial of acetazolamide

Introduction In patients with chronic obstructive pulmonary disease (COPD), oxygen delivery to the heart may be impaired during altitude travel. We assessed ECG-derived signs of cardiac ischemia, and effects of preventive acetazolamide therapy in COPD patients travelling to high altitude. Methods Patients with COPD, GOLD grade 2-3, mean±SD, FEV 1 66±11%predicted, aged 57±8years, living <1000m, were included in this analysis of secondary outcomes from a randomized, placebo-controlled, double-blind trial ( www.clinicaltrials.gov , NCT03156231 ). Exercise-electrocardiograms were recorded at the National Center of Internal Medicine and Cardiology, Bishkek (760m) and on the day of arrival at Tuja Ashu high-altitude clinic (3100m), Kyrgyzstan. Acetazolamide (375mg/day) or placebo was administered 24h before ascent and during stay at 3100m. The incidence of post-exercise ST-elevations (STE) ≥0.3mm in aVR (J+80ms) was the main outcome. Results At 760m, 3 of 49 (6%) patients randomized to placebo and 3 of 50 (6%) randomized to acetazolamide showed post-exercise STE. At 3100m under placebo, 2(4%) new STE developed and 1(2%) disappeared compared to 760m (P=0.564, McNemar Test). At 3100m under acetazolamide, 1(2%) new STE developed and 2(4%) disappeared compared to 760m (P=0.564). No treatment effect was detected (P=0.242, Fisher Exact Test). Mean difference (95%CI) in STE between post-exercise and rest at 3100m was 0.22mm(0.06 to 0.39) and 0.09mm(−0.06 to 0.24) under placebo and acetazolamide therapy (treatment effect, −0.13mm(−0.35 to 0.08, P=0.230)). Conclusions In lowlanders with moderate to severe COPD ascending to 3100m, no ECG-derived signs of cardiac ischemia emerged neither at rest nor post-exercise and this was not modified by preventive acetazolamide therapy.