Figure 1.

The electrocardiogram (ECG) taken at the time of admission showed that the patient had sinus tachycardia with a heart rate of 152 bpm (a). Following a maximum treatment regimen (200 mg/day of metoprolol, 0.25 mg/day of digoxin, and 240 mg/day of verapamil), the ECG showed sinus tachycardia with the heart rate of 120 bpm (b). After ivabradine treatment, the ECG showed sinus rhythm with the heart rate reduced to 90 bpm (c), and the ECG at discharge showed sinus rhythm within the normal range (d)