What is the "optimal" follow-up schedule for ICD patients?

In the absence of comparative studies, recommended routine follow-up (FU) intervals for implantable cardioverter defibrillator (ICD) patients range from 1 to 6 months; most patients are followed at 3 month intervals.

Six hundred and eighteen ICD patients were routinely seen 4 weeks after implant and then every 3 months. Unplanned visits (UPV) were either patient initiated or due to manufacturer recalls. FU visits included patient history/examination, ICD interrogation, pacing/sensing threshold and pacing/shock impedance. Chest X-rays were performed every 6 months. To validate FU interval recommendations, a comparative analysis on the detection of complications was performed, relying either on the information of every, or of every other FU visit, i.e., on 3 or 6 month intervals.

During 3.3+/-2.8 years, 137 complications occurred in 110 patients (17%). However, identification of only 34% was dependent on the FU schedule, since the mode of detection was ICD interrogation in 38 and history/physical examination in nine patients. The remainder was diagnosed by UPV in 47, manufacturer recall in seven, accidental discovery during device replacement in two, and routine X-ray in 34 patients. Complication free survival at 2 years was 86.4% for patients implanted before 1999, and 89.2% thereafter (P=0.003). Regarding 6 rather than 3 month FU intervals, a theoretical maximum delay of 3 months in the detection of potentially life-threatening complications would have occurred in 1.7% of all patients. For those implanted after 1999, this related to only 0.9%.

ICD-related complications detected during routine FU visits are relatively rare, particularly with newer generation ICD systems. Thus, 6 month FU intervals appear to be safe. With new developments such as patient alert features and telemedical data transmission, FU intervals in ICD clinics might even be further extended.