John J. Hayes

A population-based study of mortality among patients with atrial fibrillation or flutter

PURPOSE To determine the mortality associated with atrial flutter and atrial fibrillation in the general population. SUBJECTS AND METHODS Using the Marshfield Epidemiologic Study Area, a database that captures nearly all medical care and deaths among its 58,820 residents, we identified patients diagnosed with atrial flutter or atrial fibrillation from July 1, 1991, through June 30, 1995. Patients were followed prospectively and compared with a group of controls without these arrhythmias. RESULTS A total of 4775 person-years of follow-up were completed in 577 patients and 577 controls. Compared with controls, mortality among patients with atrial fibrillation or flutter was nearly 7.8-fold higher at 6 months (95% confidence interval [CI]: 4.1 to 15) and 2.5-fold higher (95% CI: 2.0 to 3.1; P < 0.0001) at the last follow-up (mean [+/- SD] of 3.6 +/- 2.3 years; range, 1 day to 7.3 years). At 6 months, mortality among patients with atrial flutter alone was somewhat greater than in controls and less than one third that of those with atrial fibrillation (with or without atrial flutter) (P = 0.02). At the last follow-up, however, mortality was greater among patients with atrial flutter (hazard ratio [HR] = 1.7; 95% CI: 1.2 to 2.6; P = 0.007), atrial fibrillation (HR = 2.4; 95% CI: 1.9 to 3.1; P < 0.0001), or both atrial arrhythmias (HR = 2.5; 95% CI: 1.9 to 3.3; P < 0.0001) when compared with controls in models that adjusted for cardiovascular risk factors. CONCLUSION In the general population, both atrial flutter and atrial fibrillation are independent predictors of increased late mortality. The relatively benign course during the 6-month period after the initial diagnosis of atrial flutter suggests that early diagnosis and treatment of these patients may improve their long-term survival.

Infections with Nonthoracotomy Implantable Cardioverter Defibrillators: Can These Be Prevented?

Nonthoracotomy ICDs are believed to be the best therapeutic modality for treatment of life‐threatening ventricular arrhythmias. Little is known about the risk of infection with initial implantation of these devices. We studied the incidence, clinical characteristics, and risk factors associated with infections in 1,831 patients with nonthoracotomy ICD from the Endotak‐C nonthoracotomy lead registry of Cardiac Pacemakers, Inc. A transvenous lead was implanted in 950 patients (51.9%) and a combination transvenous plus subcutaneous patch was used in 881 patients (48.1%). Nine preselected data variables were studied, and all investigators identified as having patients with infections were personally contacted. Infections occurred in 22 (1.2%) of 1,831 patients receiving this nonthoracotomy ICD system. The mean time to infection was 5.7 ± 6.5 months (range 1–25 months). Staphylococci were isolated in 58% of patients with reported infection. The presence of a subcutaneous defibrillator patch system was associated with the development of infection. Six of 950 patients (0.63%) with a totally transvenous lead system developed infection versus 16 of 838 (1.9%) patients with a transvenous lead plus subcutaneous patch system configuration (P = 0.015, Chi‐square test), with an unadjusted estimated odds ratio of 3.06 (CI 1.19–7.86). The risk of infection encountered with the nonthoracotomy ICD is low, estimated from our data to be 1.2%. Placement of a subcutaneous defibrillator patch appears to be an independent risk factor for development of infection.

Feasibility and initial results of an Internet-based pacemaker and ICD pulse generator and lead registry

HAUSER, R., et al.: Feasibility and Initial Results of an Internet‐Based Pacemaker and ICD Pulse Generator and Lead Registry. The medical community has no independent source of timely information regarding the performance of pacemaker and ICD pulse generators and leads. Accordingly, the authors established an Internet‐based registry of pacemaker and ICD pulse generator and lead failures (www.pacerandicregistry.com). During the first year, they found three previously unreported device problems that were promptly communicated to the participants. Of the failures reported, 11% of ICD and 10% of pacemaker pulse generator failures were heralded by signs other than the expected elective replacement indicator (ERI). Average ICD battery longevity was 4.0 ± 0.7 years, and average dual chamber pacemaker battery longevity was 6.8 ± 2.6 years. Disrupted insulation accounted for 54% of pacemaker and 29% of ICD lead failures. Compared to pacemaker pulse generator and lead failure, ICD device failures were more likely to cause severe clinical consequences. In conclusion, an Internet‐based registry is feasible and capable of providing timely data regarding the signs, causes, and clinical consequences of pacemaker and ICD failures.

Eptifibatide-induced acute profound thrombocytopenia presenting as refractory hypotension

A 61‐year‐old woman presented with acute coronary syndrome and was given heparin and eptifibatide in conjunction with coronary angioplasty. Shortly thereafter she became profoundly thrombocytopenic (platelets 2.0 × 109/L) and developed severe refractory hypotension. Heparin‐induced antibodies were not detected, but the patient developed strong eptifibatide‐dependent antibodies specific for platelets that appear to explain both the thrombocytopenia and the hypotensive episode. Cathet Cardiovasc Intervent 2003;58:76–79.

Narrow QRS Ventricular Tachycardia

OBJECTIVE To determine the frequency and clinical characteristics of narrow QRS ventricular tachycardia (QRS duration less than or equal to 0.11 seconds). DESIGN Consecutive survey of patients with ventricular tachycardia. SETTING Tertiary, referral-based arrhythmia service at a university medical center. PATIENTS Sequential sample of patients with inducible ventricular tachycardia who had a 12-lead electrocardiogram of the tachycardia available for review. MEASUREMENTS AND MAIN RESULTS Of 106 patients with ventricular tachycardia, 5 (4.7%; 95% CI, 2.1% to 10.6%) had ventricular tachycardia with a QRS duration less than or equal to 0.11 seconds. Three of the five patients were previously incorrectly diagnosed as having supraventricular tachycardia. All five patients had at least two electrocardiographic findings other than QRS duration to suggest ventricular tachycardia. CONCLUSIONS Narrow QRS ventricular tachycardia should be considered in the differential diagnosis of narrow QRS tachycardias. Electrocardiographic findings other than QRS duration are usually present to suggest the diagnosis.

Longitudinal study of implantable cardioverter-defibrillators: methods and clinical characteristics of patients receiving implantable cardioverter-defibrillators for primary prevention in contemporary practice

Background—Implantable cardioverter-defibrillators (ICDs) are increasingly used for primary prevention after randomized, controlled trials demonstrating that they reduce the risk of death in patients with left ventricular systolic dysfunction. The extent to which the clinical characteristics and long-term outcomes of unselected, community-based patients with left ventricular systolic dysfunction undergoing primary prevention ICD implantation in a real-world setting compare with those enrolled in the randomized, controlled trials is not well characterized. This study is being conducted to address these questions. Methods and Results—The study cohort includes consecutive patients undergoing primary prevention ICD placement between January 1, 2006 and December 31, 2009 in 7 health plans. Baseline clinical characteristics were acquired from the National Cardiovascular Data Registry ICD Registry. Longitudinal data collection is underway, and will include hospitalization, mortality, and resource use from standardized health plan data archives. Data regarding ICD therapies will be obtained through chart abstraction and adjudicated by a panel of experts in device therapy. Compared with the populations of primary prevention ICD therapy randomized, controlled trials, the cohort (n=2621) is on average significantly older (by 2.5–6.5 years), more often female, more often from racial and ethnic minority groups, and has a higher burden of coexisting conditions. The cohort is similar, however, to a national population undergoing primary prevention ICD placement. Conclusions—Patients undergoing primary prevention ICD implantation in this study differ from those enrolled in the randomized, controlled trials that established the efficacy of ICDs. Understanding a broad range of health outcomes, including ICD therapies, will provide patients, clinicians, and policy makers with contemporary data to inform decision-making.

Familial Atrioventricular Nodal Reentry Tachycardia

Dual atrioventricular nodal pathways, the substrate responsible for atrioventricular node reentry tachycardia (AVNRT), are thought to be randomly occurring congenital anomalies. This article describes 14 patients in six families, each with two or three first‐degree relatives with paroxysmal supraventricular tachycardia. Electrophysiological evidence of dual atrioventricular nodal pathways was established in all 13 patients studied, AVNRT was induced in 12 (92%), and radiofrequency ablation of the slow pathway was curative in all cases. The data suggest a hereditary contribution to the development of atrioventricular nodal pathways and AVNRT. The pattern of inheritance appears to be autosomal dominant. (PACE 2004; 27:73–76)

Atrial Flutter Versus Atrial Fibrillation in a General Population: Differences in Comorbidities Associated With Their Respective Onset

Objective: Determine and compare the prevalence of known risk factors for cardiovascular disease among unselected individuals presenting with their first ever episode of atrial flutter (AFL) and atrial fibrillation (AF). Study Design and Setting: We evaluated 11 pre-selected clinical variables including age, sex, smoking history and other potential cardiac risk factors. Using the resources of the Marshfield Epidemiologic Study Area, a population-based database, all newly diagnosed cases of either AFL or AF in the region during a 4-year period were identified. Results: Among the 472 incident cases, 76 (16.1%) had AFL and 396 (83.9%) had AF. Compared to those with AF, subjects with AFL were more likely to have had a history of chronic obstructive pulmonary disease (25% vs. 12%, P = 0.006), heart failure (28% vs. 17%, P = 0.05), and smoking (49% vs. 37%, P = 0.06). Hypertension, on the other hand, was more common among individuals with AF (63% vs. 47%, P = 0.01). Conclusion: This study represents the first report to evaluate potential differences in the conditions associated with the development of AFL versus AF. Research into the mechanisms of atrial arrhythmogenesis may lead to improved preventive and therapeutic interventions.

Catheter Ablation in the Elderly in the United States: Use in the Medicare Population from 1991 to 1998

SMITH, P.N., et al.: Catheter Ablation in the Elderly in the United States: Use in the Medicare Population from 1991 to 1998. The safety and efficacy of catheter ablation for the treatment of drug refractory cardiac arrhythmias is well established in young patients. Little is known about its effectiveness or use in the elderly. We determined trends in the use of catheter ablation in the United States Medicare population. Data were obtained from the approximately 30 million patients covered each year by Medicares fee‐for‐service program of the Health Care Financing Administration of the Department of Health and Human Services. From 1991 to 1998, Medicares fee‐for‐service beneficiaries covered 80%–93% of all adults > 65 years old in the United States. All catheter‐based ablative procedures performed in this population were identified through the use of the Current Procedural Terminology codes 93650, 93651, and 93652. Use rate per 1 million beneficiaries grew from 33 in 1991 to 603 in 1998. While during this 7‐year period the Medicare fee‐for‐service population decreased by 8%, ablations increased 16‐fold (1,608%). The use of catheter ablation in the older American grew exponentially during the 1990s. Further research is needed to determine the optimal use of this potentially curative technique in the elderly.

The role of industry in the implantation and follow-up of devices: a practitioner's perspective.

Implantable cardiac rhythm management devices continue to get more technologically complex at a pace that is difficult for most clinicians to keep up with. We have come to rely heavily on industry representatives to provide technical expertise during device implantation and follow-up. Concern has been raised about the involvement of medical device industry representatives in the clinical environment. Guidelines have been published that acknowledge the importance of device industry representatives in providing technical expertise and assistance, while also clarifying the role these representatives should play in patient care. The main principles from published policy statements are summarized, emphasizing that the physician remains responsible for the patients overall care as well as device function and programming.