Key result
Late testing of high voltage circuit integrity in ICD patients without shocks for >=12 months led to ICD reprogramming in 49% of patients and identified lead fractures requiring replacement in 1.9%.
Why the study?
Does late testing of system performance identify unsuspected lead fractures and require reprogramming in ICD patients without spontaneous shocks for ≥ 12 months?
Observational (n=105)
Does late testing of system performance identify unsuspected lead fractures and require reprogramming in ICD patients without spontaneous shocks for ≥ 12 months?
Answers are grounded in this paper and cite their sources.
Late testing of ICDs in patients without shocks for over a year can identify clinically silent lead fractures and prompt necessary reprogramming in approximately half of the patients.
UNLABELLED: One hundred five implantable cardioverter defibrillator (ICD) patients (71 +/- 9 years of age, 83% men) without spontaneous ICD discharges for > or = 12 months were tested to assess high voltage (HV) circuit integrity and the system's ability to recognize and terminate ventricular fibrillation (VF). Indications for ICD implantation were sustained ventricular tachycardia (VT) (35%), cardiac arrest (27%), and inducible VT (38%). Eighty-two percent of the patients had coronary artery disease (CAD), and the mean left ventricular ejection fraction (LVEF) was 36% +/- 13%. RESULTS: One hundred patients had inducible VF and five did not. Testing led to ICD reprogramming in 50 (49%) patients. Two (1.9%) patients required ICD replacement: (1) a 45-year-old patient with a Ventritex 110 ICD implanted for 13 months interfaced with a CPI 0062 lead implanted for 46 months could not be defibrillated internally (impedance nonmeasurable); (2) an 82-year-old patient with a 23-month-old Medtronic 7219 ICD interfaced with 6936 and 6933 leads whose defibrillation threshold (DFT) had doubled since implantation (24 J from 12 J). Lead fractures were found in both cases (proximal coil of the 0062, and subcutaneously in the 6933). Based on DFT determinations, the first shock output was programmed lower in 37 patients and higher in 10 patients. Shock pulse width was changed in one patient and the ventricular refractory period in another. No programming changes were made in 54 (51%) patients. CONCLUSIONS: (1) Late testing of HV circuit integrity in ICD patients without an ICD shock in > or = 12 months identifies previously unsuspected HV lead fractures; (2) chronic DFT testing resulted in HV output reprogramming in one-half of the patients.
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Zilo et al. (1999) conducted an observational in Implantable cardioverter defibrillator (ICD) patients without spontaneous shocks (n=105). Late testing of high voltage (HV) circuit integrity and defibrillation threshold (DFT) was evaluated on ICD reprogramming. Late testing of high voltage circuit integrity in ICD patients without shocks for >=12 months led to ICD reprogramming in 49% of patients and identified lead fractures requiring replacement in 1.9%.
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