This study assessed the cardiovascular safety of QVA149, an inhaled, once daily, bronchodilator combination containing two 24-hour bronchodilators, the long-acting β(2)-agonist indacaterol and the long-acting muscarinic antagonist glycopyrronium (NVA237). In this randomised, double-blind, placebo-controlled, parallel-group study, 257 patients with moderate-to-severe chronic obstructive pulmonary disease (COPD) were randomised to receive QVA149 (indacaterol/NVA237) 600/100 microg, 300/100 microg or 150/100 microg, indacaterol 300 μg or placebo, once daily for 14 days. The primary endpoint was change from baseline in 24-h mean heart rate versus placebo on Day 14. 255 patients were included in the safety analysis (mean age 63.8 years, 76.5% male, post-bronchodilator forced expiratory volume in one second [FEV(1)] 53.2% predicted, FEV(1)/FVC [forced vital capacity] 50.0%, mean 24-h heart rate 79.6 bpm). There were no clinically significant differences in the 24-h mean heart rate on Day 14 between the three doses of QVA149 and placebo or indacaterol. The confidence intervals of these treatment differences (contrasts) were within the pre-specified equivalence limit (-5 to 5 bpm). No clinically relevant differences in QTc interval (Fridericia's) were observed between groups on Days 1, 7 and 14. Once-daily QVA149 was well tolerated in COPD patients with a cardiovascular safety profile and overall adverse event rates similar to placebo.