Pacemaker upgrades
| First PM type | Second PM type | N=10 | Upgrade indication |
| AAI | DDD | 1 | DAV 3, syncope |
| VVI | VVI-ICD | 2 | Sustained VT, resuscitation* |
| VVI | DDD-ICD | 1 | Heart failure |
| DDD | DDD-ICD | 1 | Presyncope and documented NSVT |
| DDD | CRT-P | 1 | Generator replacement, dyssynchrony and heart failure |
| DDD | CRT-D | 2 | Heart failure (n=2), symptomatic NSVT (n=1) |
| VVI-ICD | DDD-ICD | 1 | Symptomatic bradycardia |
| VVI-ICD | CRT-D | 1 | Heart failure |
*Additionally, one individual received a second upgrade later from VVI-ICD to CRT-D.
CRT, cardiac resynchronisation therapy; DAV, distal atrioventricular block; ICD, implantable cardioverter defibrillator; NSVT, non-sustained ventricular tachycardia; PM, pacemaker.