| Pacemaker necessary | Pacemaker probably necessary | Pacemaker not necessary |
| Symptomatic bradycardia | Symptomatic patients with sinus node dysfunction with documented rates of <40 bpm without a clear-cut association between significant symptoms and the bradycardia | Asymptomatic sinus node dysfunction |
| Symptomatic sinus bradycardia due to long-term drug therapy of a type and dose for which there is no accepted alternative |
