J. C. Petitot

Failure Rates of Leads, Pulse Generators, and Programmers Have Not Diminished Over the Last 20 Years: Formal Monitoring of Performance is Still Needed

Formal Monitoring of Performance is Still Needed. In order to detect trends in the number of device or component failures that have occurred among permanent pacemaker systems since the 1970s, we reviewed the data of the five largest pacemaker manufacturers from the Bilitch Registry of permanent pacemaker pulse generators, the Stimarec failure registry, the general accounting office summaries of the United States Veterans Administration (VA) Registry of Pacemaker Leads, and the Implantable Lead Registry, from the Cleveland Clinic Lead registry, and the recalls and safety alerts issued by the United States Food and Drug Administration (FDA) over the last 20 years. The definition of failure followed the criterion, or criteria, developed within each registry and differed significantly between the registries. The 20‐year period between 1976 and 1995 was divided into 5‐year quartiles (QT): QT 1 = 1976–1980; QT2 = 1981–1985; QT 3 = 1986–1990; and QT4 = 1991–1995. For pulse generators, the number of models with failures in each quartile in the Bilitch Registry were: QT 1 = 9; QT 2 = 11; QT 3 = 17; QT 4 = 13. In Stimarec, the number of units reported as having reached a dangerous condition were: QTl = 710; QT2 = 212; QT3 = 114; QT4 = 310. From the FDA reports, the number of units included in recalls or safety alerts were: QT 3 = 6,085; QT4 = 135, 766. For permanent pacemaker leads, the numbers of failed or dangerous leads recorded in Stimarec were: QT 3 = 16; QT 4 = 32. In the VA Registry, the number of models having a below average survival was 2/92 (2.7%). In the Implantable Lead Registry, the number of models having a below average survival was 3/21 (14%). In the Cleveland Clinic series, 6/13 (46%) of lead models were recognized to have some failure involving the conductor, insulation, or connector. In the FDA reports, the number of leads involved in either recall or safety alert were: QT3 = 20,354; QT 4 = 332,105. For programmers, the number of units involved either in a recall or safety alert were: QT 3 = 11,124; QT 4 = 3,528. In all of these series, each of the five largest manufacturers had some models or units involved in each time period. This review of programs has revealed: 1. The incidence of failures, recalls, or safety alerts did not decline over time; and 2. Despite changes in technology, formal monitoring of pacemaker systems is still warranted.

Low Chronic Pacing Thresholds of Steroid-Eluting Active-Fixation Ventricular Pacemaker Leads: A Useful Alternative to Passive-Fixation Leads

Active‐fixation pacemaker leads enable pacing at various sites, have a low dislodgment rate, and are easier to extract than passive‐fixation leads, though are usually not routinely implanted in the ventricle because of their higher pacing threshold. The long‐term pacing threshold associated with an active‐fixation steroid‐eluting lead was prospectively measured in 18 women and 20 men. At a mean follow‐up of 14 months (range 3–25 months), pacing threshold increased from 0.71 ± 0.29 V to 0.96 ± 0.28 V (P = 0.01) between implant and the first month of follow‐up, then remained stable over time, consistently allowing the long‐term programming of the ventricular output at 2.5 V, while lead impedance remained stable (from 647 ± 161 Ω at implant to 666 ± 122 Ω at last follow‐up). If the long‐term performance of this type of lead is confirmed, the routine implantation of ventricular steroid‐eluting active‐fixation leads should be considered since lead extraction has become a major concern.

Spontaneous Versus Extraction Related Injuries Associated With Accufix J‐wire Atrial Pacemaker Lead: Tracking Changes in Patient Management

To make recommendations for management of potentially fatal failure of the Accufix series of atrial J‐wire permanent pacemaker leads, we closely monitored the number of injuries and fatalities resulting either from spontaneous fracture of the J‐wire or from attempts to extract the lead. In a population of 30,357 patients, 2,298 patients are enrolled in a prospective follow‐up Multicenter Study, the remainder are patients with known clinical status from voluntary reporting, and 2,992 patients died following implant. In the remaining 27,365 patients, 6 deaths have been attributed to J‐wire related injury (J‐inj) while 13 were complications (E‐inj) associated with 4,076 lead extraction procedures (3,974 intravascular (intra)/ 102 primary thoracotomy (PT). The date of occurrences were from 1994 to November 1997. Conclusions: (1) Since lead extractions were not conducted in a controlled study, it is not known whether the deaths associated with lead extraction is in excess of what would have occurred if these leads had not been removed in this specific subset.

Kaplan-Meier analysis of freedom from extraction or death in patients with an Accufix J retention wire atrial permanent pacemaker lead: A potential management tool

Morbidity (36 cases) and mortality (6 cases) have been reported in patients with Accufix J retention wire atrial leads. This has resulted in ongoing patient fluoroscopic monitoring as well as lead extractions. The estimated implanted worldwide population is 40,860. Estimating the size of the remaining population at risk is an important tool for assessing patient management guidelines. Results: The Kaplan‐Meier method can be used to calculate the cumulative probability of remaining free of extraction and death for patients based on implant duration. The individual Kaplan‐Meier curves for lead extraction and patient survival can also be computed. Based on the Multicenter Study (MCS) population of 2,298 patients, the probability that a patient is alive with the lead still implanted at 5 years implant duration is 52.5%. The event‐free survival rate at 5 years implant duration is 81.3%. The corresponding probability of remaining free from injury due to the J‐wire is 99.9% at 5 years implant duration. Assuming similar rates of death and extraction, these results can be extrapolated to the world wide population. Conclusions: The management of Accufix patients must consider patient longevity, the probability of J‐wire morbidity/mortality, and the probability of extraction complication morbidity/mortality. The probability of remaining at risk as a function of time from implant can be calculated from the events known in the MCS patient population. These event‐free survival estimates can be used to identify subsets of the population at greater or lesser risk based on various clinical parameters.

Cumulative Hazard Analysis of J‐Wire Fracture in the Accufix Series of Atrial Permanent Pacemaker Leads

To permit a more complete analysis of J‐wire fracture in the Accufix series of atrial permanent pacemaker leads, the time to occurrence of all known fractures and injuries has been redefined relative to the duration of risk exposure, that is, according to the interval of time between implant and occurrence of the event. This redefinition permits application of a cumulative hazards model to the data, which previously has not been explored. Predictors of J‐wire fracture can be tested using this method. This also permits parametric curve‐fitting for determination of linearity or constancy of risk of events over time. Results: Among 2,063 Multicenter Study (MCS) leads analyzed, 381 fractures of the J‐wire were identified. Stratified analysis based on cumulative hazard curves identified a more open shape of the J‐wire as predictive of fracture, which supports the results previously reported based on logistic regression analysis. Fitting a Weibull curve to the cumulative hazard of J‐wire fracture gives a shape parameter equal to 0.85. This value indicates that the instantaneous hazard of J‐wire fracture decreased over time from implant. Conclusions: (1) The cumulative hazard function can be used to examine predictors of J‐wire fracture and preliminary findings support the previously identified predictor of J shape; (2) Based on these analyses, the rate of J‐wire fracture appears to decrease slightly as time from implant increases.

Risks of Delayed Potentials in Pacemaker Patients Prone to Ventricular Tachycardia

Late potentials occurring after completion of the QRS complex have been observed in patients prone to ventricular tachycardia. They were recorded either during epicardial studies or in the catheterization laboratory. This paper describes such abnormal myocardial activity and discusses their potential effects on cardiac pacemakers.