Douglas Gohn

Clinical Benefits of Remote Versus Transtelephonic Monitoring of Implanted Pacemakers

OBJECTIVES The purpose of this study was to evaluate remote pacemaker interrogation for the earlier diagnosis of clinically actionable events compared with traditional transtelephonic monitoring and routine in-person evaluation. BACKGROUND Pacemaker patient follow-up procedures have evolved from evaluating devices with little programmability and diagnostic information solely in person to transtelephonic rhythm strip recordings that allow monitoring of basic device function. More recently developed remote monitoring technology leverages expanded device capabilities, augmenting traditional transtelephonic monitoring to evaluate patients via full device interrogation. METHODS The time to first diagnosis of a clinically actionable event was compared in patients who were followed by remote interrogation (Remote) and those who were followed per standard of care with office visits augmented by transtelephonic monitoring (Control). Patients were randomized 2:1. Remote arm patients transmitted pacemaker information at 3-month intervals. Control arm patients with a single-chamber pacemaker transmitted at 2-month intervals. Control arm patients with dual-chamber devices transmitted at 2-month intervals with an office visit at 6 months. All patients were seen in office at 12 months. RESULTS The mean time to first diagnosis of clinically actionable events was earlier in the Remote arm (5.7 months) than in the Control arm (7.7 months). Three (2%) of the 190 events in the Control arm and 446 (66%) of 676 events in the Remote arm were identified remotely. CONCLUSIONS The strategic use of remote pacemaker interrogation follow-up detects actionable events that are potentially important more quickly and more frequently than transtelephonic rhythm strip recordings. The use of transtelephonic rhythm strips for pacemaker follow-up is of little value except for battery status determinations. (PREFER [Pacemaker Remote Follow-up Evaluation and Review]; NCT00294645).

Prospective randomized comparison of cooled radiofrequency versus standard radiofrequency energy for ablation of typical atrial flutter.

ATIGA, W.L., et al.: Prospective Randomized Comparison of Cooled Radiofrequency Versus Standard Radiofrequency Energy for Ablation of Typical Atrial Flutter. In patients with atrial flutter, conventional RF ablation may not result in complete isthmus block. This prospective, randomized study tested the hypothesis that the cooled RF ablation is safe and facilitates the achievement of isthmus block with fewer RF applications than with standard ablation for typical atrial flutter. Isthmus ablation was performed in 59 patients (40 men, 64 ± 14 years) with type I atrial flutter using standard RF (n = 31) or cooled RF (n = 28) catheters with crossover after 12 unsuccessful RF applications. The endpoint was bidirectional isthmus block or a total of 24 unsuccessful RF applications. After the first 12 RF applications, 17 (55%) of 31 standard RF and 22 (79%) of 28 cooled RF patients had bidirectional isthmus block (P < 0.05). After the remaining patients crossed over to the alternate RF ablation system and underwent up to 12 more RF applications, bidirectional isthmus block had been demonstrated in 27 (87%) of 31 standard RF and 25 (89%) of 28 cooled RF patients (P = NS). Isthmus block was not achieved within 24 RF applications in four standard and three cooled RF patients. Mean measured tip temperatures for cooled RF were lower than for standard RF (38.5°C ± 6.98°C vs 57.2°C ± 7.42°C, P < 0.0001). Peak temperatures were also lower for cooled RF compared to standard RF (45.7°C ± 22.7°C vs 63.4°C ± 9.87°C, P < 0.0001). Importantly, mean power delivered was significantly higher for cooled than for standard RF (42.3 ± 9.48 vs 34.0 ± 14.0 W, P < 0.0001). There were no serious complications for either ablation system. During a 12.8 ± 3.76‐month follow‐up, there were two atrial flutter recurrences in the cooled RF group and four in the standard RF group (P = NS). In patients with type I atrial flutter, ablation with the cooled RF catheter is as safe as, and facilitates creation of bidirectional isthmus block more rapidly than, standard RF ablation.

Implantable Cardioverter Defibrillator Implanted by Nonthoracotomy Approach: Initial Clinical Experience with the Redesigned Transvenous Lead System

Standard implantation procedure for the implantable Cardioverter defibrillator (ICD) has traditionary required a thoracotomy approach. A newly revised nonthoracotomy defibrillator lead system that uses a single transvenous tripolar endocardial lead alone or in combination with a subcutaneous/submuscular patch lead was introduced into clinical trials in September, 1990. Fourteen patients requiring a Cardioverter defibrillafor for recurrent sustained ventricular tachycardia (eight patients) or aborted sudden cardiac death (six patients) were evaluated for implantation of this lead system. Primary successful lead system implantation was obtained in nine patients. The remaining five patients had unacceptably high defibrillation thresholds (DFTs) for implantation. One of the nine initially successful implants demonstrated unacceptable DFTs and cross‐talk inhibition from a permanent pacemaker necessitating removal of the nonthoracotomy lead system and replacement with a conventional lead system via thoracotomy. All remaining primary implanted patients experienced successful conversion of induced ventricular fibrillation prior to hospital discharge. Continued follow‐up and greater experience to confirm the durability and efficacy of the nonthoracotomy AICD lead system are needed.

Six-Year Clinical Experience with the Automatic Implantable Cardioverter Defibrillator

Since their introduction into clinical practice by Mirowski^ just 10 years ago, implantable cardioverter defibrillators have assumed a progressively more important role in the management of drug refractory ventricular arrhythmias. Despite implantation of over 18,000 devices worldwide,^ the number of series reporting over 200 patients remains limited.^* With several manufacturers applying for market release of new internal defibrillators, it is now more important to understand the risks versus benefits of internal defibrillator implantation. In this series we report our results in a large patient group.

Analysis of deaths in patients with an implantable cardioverter defibrillator.

The cause of death and clinical characteristics of 26 patients that died after impIantable Cardioverter defibril‐lator placement were reviewed and compared to the 145 patients still living after a mean follow‐up of 17 months. Operative mortality was 4% (7/171) and resulted from postoperative ventricular arrhythmias (four patients), heart failure (two patients), and respiratory failure (one patient). Operative mortality was significantly higher (1.7% vs 9.6%, P < 0.05) following concomitant surgical procedures. Total late mortality was 11% (18/171). Thirteen deaths (75%) occurred in‐hospital from progressive deterioration of left ventricular function (nine patients), arrhythmia (two patients), and noncardiac causes (two patients). Outpatient mortality was 3.5% (6/171) and resulted from presumed sudden cardiac death in five of six patients; two of the five had devices that were inactive, one had high defibrillation thresholds, and two had suspected baradyarrhythmic deaths. One postoperative death and one late in‐hospital death were also considered sudden cardiac deaths for a total of seven patients with defibrillation system failures. By multivariant analysis, preoperative clinical characteristics associated with a worse prognosis following defibrillator implantation were identified: presentation as ventricular tachycardia (P < 0.02), induction of sustained monomorphic ventricular tachycardia (P < 0.05), poor left ventricular performance (P < 0.01), poor functional status (P < 0.001), and the use of diuretics (P < 0.01). Frequent device discharges (P < 0.001) and concomitant antitachycardia pacing systems (P < 0.001) were markers for greater arrhythmia recurrence and were potent predictors of a worse prognosis and particularly sudden death.