Longevity of implantable cardioverter-defibrillators, influencing factors, and comparison to industry-projected longevity.

BACKGROUND: Because the best possible device longevity is crucial (i.e., risk of infection with premature device exchange, current cost-effectiveness calculations depending on reasonable longevity, patient comfort), industry-independent real-life data are fundamental. However, only limited independent data on the longevity of implantable cardioverter-defibrillators (ICDs) are available. OBJECTIVE: The purpose of this study was to determine ICD device longevity and influencing factors. METHODS: From a prospective database, we studied overall device longevity and identified those devices with replacement for battery depletion or prolonged charge time. For every device, we determined factors that included averaged shocks, pacing percentage, pacing mode, device size, and time of implant. Survival probabilities at different time intervals were calculated, and Kaplan-Meier and Cox regression analyses were used. Observed longevity was compared to industry-projected longevity obtained from product performance reports. RESULTS: A total of 644 ICDs (Medtronic 317, Guidant 189, St. Jude 118, Intermedics 20) were implanted in 499 patients. During follow-up, 163 (25.3%) ICDs were replaced. Manufacturer, time of implant, pacing mode, pacing percentage, and capacitor reformation interval influenced longevity, whereas device size and number of shocks did not. Median longevity was 7.6 years for Medtronic devices, 5.0 years for Guidant devices, and 3.8 years for St. Jude devices. After 5 years, only 70% of ICDs were still in service compared to the 80% projected by industry. CONCLUSION: Marked differences in device longevity among manufacturers cannot be explained by pacing mode, number of shocks, or pacing percentage only. Overall, device performance requires further improvement for the sake of patient health and cost.

Routine echocardiography after radiofrequency ablation: to flog a dead horse?

AIMS: Radiofrequency ablation (RFA) is frequently used to treat sustained arrhythmias. One major complication is pericardial effusion-tamponade. Therefore, many centres perform echocardiography after interventions, but data on necessity of such routine procedures are scarce. METHODS AND RESULTS: We included 510 patients with RFA and compared echocardiographic results acquired before and <24 h after intervention. We defined pericardial effusion as 'small', if <10 mm in diastole, 'moderate' if >10 mm, 'large' if >20 mm, or tamponade (>20 mm with haemodynamic compromise). Age was 55 +/- 16 years, 40% were females. Thirty-five percentage underwent RFA for atrioventricular nodal re-entrant tachycardia (AVNRT), 28% for atrial flutter, 15% for atrial fibrillation (AF), 12% for Wolff-Parkinson-White (WPW) syndrome, and 10% for different other arrhythmias. In 16 patients (3.2%), small asymptomatic effusions were detected. The only moderate effusion was suspected due to procedure circumstances. Radiofrequency ablation for AF had a higher incidence compared to AVNRT and flutter (P = 0.001 and <0.0001, respectively) or to WPW syndrome (P = 0.06). CONCLUSION: Numbers of significant pericardial effusion as detected by routine echocardiography were low (3.6%) and clinically relevant effusions absent. We thus recommend performing echocardiography after RFA only, if effusion is suspected clinically or if RFA was performed for AF, due to the high incidence of effusions with this type of ablation.

Value of VDD-pacing systems in patients with atrioventricular block: experience over a decade.

BACKGROUND: Even though current guidelines suggest the use of VDD pacemakers in patients with AV block and normal sinus node function, a DDD system is often preferred for fear of either long-term atrial undersensing or late sinus node dysfunction and the resultant need for system upgrades. METHODS: We evaluated the long-term follow-up of all VDD pacemakers implanted in our center between 1992 and 2001 regarding atrial sensing, maintenance of AV synchrony, incidence of atrial fibrillation (AF), or the need for system upgrade, respectively. RESULTS: 320 consecutive patients (56% men, age 75+/-13 years) received a VDD pacemaker for the following indications: third-degree AV block 54%, second-degree AV block 34%, fascicular block with first-degree AV block and syncope 6%, others 6%. 138 patients (43%) died during follow-up, 3.8+/-2.3 years after implantation. Follow-up duration was 6.1+/-2.5 years in the remaining patients. At the last follow-up, 268 pacemakers (84%) were programmed to the VDD mode, 47 pacemakers (15%) were permanently programmed to the VVI mode (AF 36, undersensing 7, others 4, respectively). In five patients a DDD upgrade was necessary for sinus node dysfunction (3) or lead defect (2). Lead revision was performed in 19 patients (6%) (ventricular lead dislocation 7, atrial undersensing 6, lead fracture 3, others 2, respectively). CONCLUSION: VDD pacemakers have an excellent long-term performance in patients with AV block. They have a very low incidence of lead revisions for atrial undersensing (2%) and DDD upgrades for secondary sinus node dysfunction (1%).

Long-term performance of a simple algorithm for early discharge after ruling out acute coronary syndrome: a prospective multicenter trial.

STUDY OBJECTIVES: To test the short- and long-term performance of a simple algorithm to detect or rule out acute coronary artery disease (CAD) in patients referred with acute chest pain (CP). DESIGN: Prospective, multicenter study with 30-day and 1-year follow-ups. SETTING: Emergency and coronary care units of two university hospitals and four affiliated teaching hospitals in a suburban region of northern Switzerland. PATIENTS: One hundred sixty-one consecutive patients referred with acute CP with a high CAD risk profile underwent exercise testing (ET) within 24 h if results of two troponin tests and ECG remained normal within 6 h. The patients were discharged if ET results were negative or underwent angiography if the results were positive. MEASUREMENTS AND RESULTS: The primary end point was survival free of death, myocardial infarction (MI), and acute coronary syndrome, as well as the correct diagnosis of CAD in need of revascularization. Failure of the algorithm included events not predicted and false-positive ET results. Symptom-limited ET was performed in 142 patients, and stress imaging was performed in 17 patients. Discharge within 24 h was possible in 76%. Angiography in 21 patients showed no CAD in 4 patients, whereas revascularization was necessary in 17 patients. During follow-up, three patients had an MI (one fatal) and two patients had unstable angina, for an event rate of 3.1%/yr. Overall sensitivity of the algorithm to detect CAD was 71%, whereby six of seven false-positive ET results were due to exercise-induced CP without ECG changes. More importantly, the negative predictive value was 96.4%, indicating that this simple algorithm failed to identify only 3.6% of patients at risk for future events. CONCLUSIONS: Discharge within 24 h after onset of acute CP in high-risk CAD patients is safe, irrespective of CAD history, if ECG findings remain unchanged and troponin test results are normal within 6 h, and if results of adequate ET are negative.