Key result
Dual chamber ICDs exhibited undersensing in 20% of patients and oversensing in 10%, with oversensing significantly associated with pacing before the index event (80% vs 11.9%, P<0.001).
Why the study?
What is the prevalence of sensing abnormalities in patients with dual chamber ICDs?
Observational (n=48)
What is the prevalence of sensing abnormalities in patients with dual chamber ICDs?
Dual chamber ICDs generally demonstrate accurate sensing, but oversensing leading to inappropriate shocks occurs in 10% of patients, especially those requiring frequent pacing.
Oversensing may warrant monitoring in paced dual-chamber ICD patients; leaves open optimal programming strategies.
BACKGROUND: The clinical efficacy of ICD therapy depends on accurate sensing of intracardiac signals and sensing algorithms. We investigated the occurrence of sensing abnormalities in patients with dual chamber ICDs. METHODS: The study group consisted of all patients with dual chamber ICDs enrolled in the LESS trial and patients implanted with dual chamber ICDs at a single center between January 1997 and July 2000. Electrograms of spontaneous ventricular arrhythmias requiring device intervention were analyzed. RESULTS: A total of 48 patients met the criteria for enrollment. Among the 244 episodes, 215 (88%) were due to ventricular tachycardia and 29 (12%) were due to ventricular fibrillation. Overall undersensing was infrequent with 12 (20%) patients exhibiting on average 2.2 undersensed beats during 26 episodes of ventricular arrhythmias. There was no delay in therapy due to undersensing. Oversensing occurred in 5 (10%) patients resulting in 13 (2.7%) episodes of inappropriate therapy. None of the patients had any lead abnormalities and oversensing resolved after device reprogramming in 4 patients while 1 patient required a separate rate sensing lead. Among patients with oversensing, 4 out of 5 were pacing before the index event while among patients with no oversensing only 5 out of 42 were pacing (P<0.001). CONCLUSIONS: Dual chamber ICDs demonstrate outstanding accuracy of sensing. However, because of the selection of patient population requiring more frequent pacing, oversensing occurs with a significant frequency. Meticulous evaluation in such patients is necessary to minimize the likelihood of oversensing and inappropriate shocks.
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Saeed et al. (2003) conducted an observational in Ventricular arrhythmias in patients with dual chamber ICDs (n=48). Dual chamber ICDs was evaluated on Occurrence of sensing abnormalities (undersensing and oversensing). Dual chamber ICDs exhibited undersensing in 20% of patients and oversensing in 10%, with oversensing significantly associated with pacing before the index event (80% vs 11.9%, P<0.001).
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