We conducted a randomized , double-blind , placebo-controlled trial of ivabradine , added to standard background therapy , in 19,102 patients who had both stable coronary artery disease without clinical heart failure and a heart rate of 70 beats per minute or more ( including 12,049 patients with activity-limiting angina [ class II on the Canadian Cardiovascular Society scale , which ranges from I to IV , with higher classes indicating greater limitations on physical activity owing to angina ] ) .