Ambulatory ECG monitoring in patients with recurrent syncope is nondiagnostic in the majority of cases. Recently, an ECG implantable loop recorder (ILR) has been introduced. The ILR performs continuous ECG monitoring over a period of at least 14 months. From February 1997 to September 1999, 35 patients underwent implantation of an ILR. During a mean follow-up of 11 +/- 8 months, 24 (69%) patients had recurrent syncope or presyncope events. Four (11%) patients were not capable of activating the ILR to save the event. A symptom-rhythm correlation could be studied in 20 (83%) of 24 patients. Forty of 44 recurrences were captured by the ILR. There were 14 (40%) patients with at least one syncopal episode. An arrhythmic cause for syncope was found in eight of them (bradycardia in four and tachycardia in four). In the other six patients the heart rhythm was normal. In 17 (49%) patients with 1-year follow-up, the mean syncope event rate 12 months before ILR implantation was 4.7 +/- 2.4, whereas the mean syncope event rate 12 months after ILR implantation was 1.3 +/- 0.7 (P < 0.01). Resolution of symptoms was observed in 6 (17%) patients. These patients were significantly younger than patients without resolution (50 +/- 18 vs 69 +/- 14 years, p < 0.01) and five were women. Three (9%) patients died during follow-up, all of them were noncompliant during their follow-up. In conclusion, the ILR made symptom-rhythm correlation possible in 83% of patients with recurrent syncope. Syncope recurrences decreased significantly after implantation of the device, especially in the younger patients. Noncompliant patients had a high mortality rate.

Programming maximum right ventricular output in a patient with a biventricular implanted cardioverter defibrillator resulted in ventricular oversensing and ventricular safety pacing in the same cardiac cycle.