Approach to suspected sinus node dysfunction (SND)

AV: atrioventricular; ECG: electrocardiogram; ETT: exercise treadmill test; MI: myocardial infarction; SND: sinus node dysfunction.

* SND should be suspected in a patient ≥65 years of age with any of the following:

• Unexplained syncope or presyncope
• Symptoms (eg, lightheadedness, fatigue, dyspnea) with activity, especially if the resting heart rate is <60 bpm
• ECG evidence of abnormal sinus node function (eg, sinus bradycardia <50 bpm, sinus pause >3 seconds, sinus arrest, sinoatrial nodal exit block)

¶ Chronotropic incompetence is present if there is minimal augmentation (eg, ≤20%) of the heart rate with exercise, especially if the resting heart rate is <60 bpm.