Key result
Automatic verification of capture (AVC) algorithms prevented exit block despite a permanent right ventricular pacing threshold increase above 1.5 V in 12.8% of patients over 49 months.
Why the study?
What is the long-term behavior of right ventricular pacing thresholds in patients with pacemakers using automatic verification of capture algorithms?
Observational (n=321)
What is the long-term behavior of right ventricular pacing thresholds in patients with pacemakers using automatic verification of capture algorithms?
Automatic verification of capture algorithms safely manage long-term right ventricular pacing threshold increases, which occur in about 13% of patients, preventing exit block and maximizing device longevity.
Supports AVC algorithms for averting exit block in threshold rises; extends observational data but leaves randomized confirmation open.
BACKGROUND: We studied long-term right ventricular (RV) pacing threshold (RVPT) behavior in patients consecutively implanted with pacemakers capable of automatic output reprogramming tracked by automatic RV threshold measurement (automatic verification of capture [AVC]). METHODS: All the patients had state-of-the art steroid-eluting bipolar pacing leads and were RV-paced by an AVC algorithm from the three American manufacturers. Follow-up occurred twice in the first year after implantation, then yearly until approaching elective replacement indicator. RESULTS: Three hundred and twenty-one patients aged 73 ± 12 years were observed for 49 ± 26 months on average. At implantation, RVPT was 0.54 ± 0.2 V at 0.4 ms at an average 774 ± 217 Ω impedance. Forty-one of the 321 patients (12.8%) had a permanent RVPT increase above 1.5 V at 0.4 ms: RVPT was between 1.6 and 2.5 V in 29 of 321 (9%) patients, whereas it was between 2.6 and 3.5 V in seven of 321 (2.2%) patients, and >3.5 V in five of 321 (1.5%) patients. No exit block occurred because of automatic RV output adjustment by AVC algorithms. No predictor of RVPT increase was found at multivariable analysis. The maximum RVPT increase occurred within 12 months from implantation in 19 of 321 (5.9%) patients, between the first and the second year in 12 of 321 (3.7%), between the second and the sixth year in eight of 321 (2.5%), and after the sixth year in two of 321 (0.6%). CONCLUSION: Despite technologic improvement in lead manufacturing, long-term increase of the RVPT occurs in about 13% of patients, possibly representing a serious safety issue in 3.7% when 2.5 V at 0.4 ms is exceeded. AVC algorithms can improve patients' safety by automatic tailoring of the pacing output to threshold fluctuations, while maximizing device longevity.
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Biffi et al. (2010) conducted an observational in Pacemaker implantation (n=321). Right ventricular pacing with automatic verification of capture (AVC) was evaluated on Permanent right ventricular pacing threshold (RVPT) increase above 1.5 V at 0.4 ms. Automatic verification of capture (AVC) algorithms prevented exit block despite a permanent right ventricular pacing threshold increase above 1.5 V in 12.8% of patients over 49 months.
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