Sensing/pacing lead complications with a newer generation implantable cardioverter-defibrillator: worldwide experience from the Guardian ATP 4210 clinical trial.

OBJECTIVES: This report describes the sensing/pacing lead complications that developed during a worldwide clinical trial of a new implantable cardioverter-defibrillator. BACKGROUND: The reliability of the leads used for sensing and pacing with the implantable cardioverter-defibrillator has not been adequately studied. METHODS: The Guardian ATP 4210 was implanted in 302 patients. The sensing/pacing leads consisted of either two unipolar epicardial electrodes or a bipolar endocardial electrode from a variety of manufacturers. RESULTS: During a mean follow-up period of 380 days, 39 patients (12.9%) required reoperation because their device developed sensing/pacing lead system complications. The most common clinical presentation was device oversensing (multiple tachycardia or noise detections or inappropriate shocks), which was observed in 27 patients, whereas elevated pacing thresholds were seen in 10 patients. Forty-one (11.8%) of 347 implanted lead systems required revision. The mean time to revision was 156 +/- 145 days. Actuarial lead survival rate at 1 and 3 years was 89% and 79%, respectively. Epicardial lead systems required significantly (p < 0.05) more revision than did endocardial systems, but when adapter problems were excluded, the revision rates of epicardial and endocardial leads were similar. Causes of lead system failures included adapter connection problems, lead dislodgement and insulation disruption. Predictors of lead revision were use of an epicardial lead system or an adapter. CONCLUSIONS: A high rate of sensing/pacing lead complications was found with this newer generation implantable cardioverter-defibrillator. The enhanced diagnostic and data storage capabilities of this implantable cardioverter-defibrillator facilitated the recognition and troubleshooting of these complications. These findings emphasize the need for careful surveillance and testing of implantable cardioverter-defibrillator sensing/pacing leads during follow-up.

Clinical benefit of dual chamber pacing in hypertrophic cardiomyopathy: a case report.

This case study presents evidence that angioplasty and dual chamber pacing can be used as a therapeutic alternative to coronary artery bypass grafting and myectomy. The following case report describes this treatment option in a patient with hypertrophic cardiomyopathy and ischemic heart disease who refused surgery. A severe coronary lesion was successfully treated with percutaneous transluminal coronary angioplasty (PTCA). Subsequent deterioration of the patient's clinical status occurred, yet a repeat heart catheterization revealed no angiographic changes from the PTCA. The left ventricular outflow gradient was 97 mmHg despite optimizing medical therapy. Temporary pacing leads were inserted and the patient was DDD paced at 70 ppm while measuring the LV gradient at varying AV intervals. Significant reduction of the outflow tract gradient occurred at all AV intervals tested. Although the pressure gradient decreased during VVI pacing, atrial contribution was necessary to achieve the desired hemodynamic benefit. A permanent DDDR pacemaker was implanted with satisfactory clinical results.

Exploration of the precision of classifying sudden cardiac death. Implications for the interpretation of clinical trials.

BACKGROUND: As cardiovascular clinical trials improve in sophistication and therapies target specific cardiac mechanisms of death, a more objective and precise system to identify specific cause of death is needed. Ideally, sudden cardiac death would describe patients dying of ventricular tachycardia and ventricular fibrillation. In this context, we explored the precision of current sudden death classification and implications for clinical trials. METHODS AND RESULTS: Deaths were analyzed in 834 patients who received an automatic implantable cardioverter-defibrillator (ICD). Three arrhythmia experts used a standard prospective classification system to classify deaths into accepted categories: sudden cardiac, nonsudden cardiac, and noncardiac. New aspects to this study included analysis of autopsy results and ICD interrogation for arrhythmias at the time of death. All of the patients receiving the ICD previously had documented sustained ventricular tachycardia/fibrillation or cardiac arrest. Of the 109 subsequent deaths in the 834-patient database, 17 (16%) were classified as sudden cardiac. Compared with the nonsudden cardiac and noncardiac categories, sudden cardiac death was more often identified in outpatients (59% versus 10%) and witnessed less often (41% versus 86%; both P < .001). The autopsy information contradicted and changed the clinical perception of a "sudden cardiac death" in 7 cases (myocardial infarction [n = 1], pulmonary embolism [n = 2], cerebral infarction [n = 1], ruptured thoracic [n = 1], and abdominal aortic aneurysms [n = 2]). Interpretable ICD interrogation was available in 53% of the deaths (47% unavailable: buried, programmed off, or other technical reasons). When evaluated, only 7 of 17 "sudden deaths" were associated with ICD discharges near the time of death. CONCLUSIONS: Even in a group of patients with an ICD, deaths classified as sudden cardiac frequently were not associated with ventricular tachycardia or ventricular fibrillation and were often noncardiac. It is possible to create a wide range of sudden cardiac death rates (more than fourfold) using the identical clinical database despite objective, prespecified criteria. Autopsy results frequently reveal noncardiac causes of clinical events simulating sudden cardiac death. ICD interrogation revealed that ICD discharges were often related to terminal arrhythmias incidental to the primary pathophysiological process leading to death.