Implantable cardioverter defibrillator utilization among device recipients presenting exclusively with syncope or near-syncope.

INTRODUCTION: Implantable cardioverter defibrillators (ICDs) are occasionally used in presumed high-risk patients with electrocardiographically undocumented syncope, although the incidence of ventricular tachyarrhythmias in this population is not well defined. METHODS AND RESULTS: We studied 33 consecutive patients receiving an ICD (67% nonthoracotomy and 70% tiered therapy) after electrophysiologic testing for unmonitored "syncope" (n = 29) or "near-syncope" (n = 4). Atherosclerotic heart disease was present in 24 (73%); mean left ventricular ejection fraction (LVEF) was 0.39 +/- 0.15; and sustained monomorphic ventricular tachycardia (SMVT) was inducible in 18 (55%). Over a median follow-up of 17 months (range 4 to 61), 12 patients (36%) received > or = 1 appropriate ICD discharge triggered by SMVT (cycle length 230 to 375 msec) in 10 and ventricular flutter or fibrillation in 2--without concomitant antiarrhythmic medication in 8 of 12 cases. Inducible SMVT and LVEF < or = 0.35 were statistically significant, independent predictors of an appropriate ICD discharge (P < 0.02 and P < 0.03, respectively). Estimated 1-year cumulative survival free of appropriate discharge was 34% versus 87%, respectively, in patients with versus without inducible SMVT (P < 0.02), and 18% versus 56%, respectively, in patients with LVEF < or = 0.35 versus LVEF > 0.35 (P < 0.03). CONCLUSION: In this highly select, multicenter population of ICD recipients with electrocardiographically undocumented syncope, a substantial incidence of appropriate device discharges was observed, particularly in patients with inducible SMVT and LVEF < or = 0.35. These findings support the notion that, in patients with LV dysfunction and inducible SMVT, ventricular tachyarrhythmias are likely to account for episodes of syncope or near-syncope.

Ventriculoatrial conduction capability and prevalence of 1:1 retrograde conduction during inducible sustained monomorphic ventricular tachycardia in 305 implantable cardioverter defibrillator recipients.

Despite the advent of dual chamber ICDs, differentiation of VT (SMVT) with 1:1 VA conduction will remain a challenge. In this study, VA conduction capability and prevalence of inducible sustained monomorphic (SM) VT with 1:1 VA conduction was assessed in 305 ICD recipients. SMVT with a mean cycle length (CL) of 304 +/- 61 ms was induced in 161 (53%) patients. Twenty-six percent of the patients maintained 1:1 VA conduction to CL < or = 400 ms during incremental ventricular pacing, regardless of presenting tachyarrhythmia or presence of inducible SMVT. Among ten patients who had inducible SMVT with possible 1:1 VA conduction (based on SMVT CL comparable to the shortest CL associated with 1:1 retrograde conduction during ventricular pacing), all seven with available intracardiac tracings had documented 1:1 VA conduction during the induced SMVT--representing 4.4% of the patients with inducible SMVT (95% CI 1.2%-7.6%), and 2.3% of the entire ICD cohort (95% CI 0.6%-4.0%). We conclude that about one-fifth of ICD recipients possess 1:1 VA conduction to CL < or = 400 ms and that inducible SMVT with 1:1 VA conduction can be demonstrated in a small but nonnegligible proportion of ICD recipients. These data are relevant to the design of tachyarrhythmia-discrimination algorithms for dual chamber ICDs.

Determinants of improvement in exercise capacity in patients undergoing cardiac rehabilitation.

In order to identify patients who benefit most from a cardiac rehabilitation program, we studied retrospectively all patients who completed a 3-month comprehensive cardiac rehabilitation program during a 2-year period. Questionnaires regarding physical exercise habits were sent to 122 patients and returned by 117 (96%) of them (53 post-acute myocardial infarction, 50 post-coronary artery bypass surgery, 14 post-infarction and surgery, 2 post-angioplasty). Exercise capacity (subset of 66 patients) improved by 19% after rehabilitation (7.8 +/- 3.1 to 9.3 +/- 2.7 METs, p < 0.0001). Univariate and multivariate analysis identified initial exercise capacity as the only independent variable predicting improvement in exercise performance (inverse relationship) (r2 = 0.24, p < 0.0001). The improvement was not related to age, sex, left ventricular function or time from cardiac event to rehabilitation. Patients recovering from both infarction and coronary artery bypass surgery showed a greater improvement (delta exercise capacity 2.8 +/- 1.4 METs) than patients after myocardial infarction alone (delta exercise capacity 0.8 +/- 2 METs, p < 0.02). Improvement was sustained for up to 2 years after completion of the program.

Pacemaker endocarditis. Report of 44 cases and review of the literature.

We conducted a retrospective study to characterize the clinical course, microbiologic spectrum, and risk factors for endocarditis and for associated mortality in a large series of patients with documented pacemaker endocarditis. Using a computerized search through the medical records of 10 major hospitals in Israel from 1982 to 1992, and carefully reviewing the charts, we identified 44 patients with pacemaker endocarditis. The cases were categorized as definite (n = 25), probable (n = 12), or possible (n = 7) infective endocarditis based on strict case definition. Fever and chills were the most common symptoms. Increased ESR, leukocytosis, microscopic hematuria, and anemia were the most common laboratory findings. A relatively high proportion of the patients were diabetic. The most common source of endocarditis was infection acquired by the placement procedure or infection of the pacemaker pouch. Demographic, clinical, and laboratory features were similar to those of endocarditis patients of a similar age range without pacemakers, although the frequency of fever and chills was higher in our patients than in those patients and splenomegaly, vascular embolic phenomena, and new or changing murmurs were rare in our patients. The major pathogens were Staphylococcus aureus and Staphylococcus epidermidis, similar to other series of pacemaker-associated bacteremia and similar to the microbiologic findings of early prosthetic-valve endocarditis. However, this microbiologic profile is different from that of native-valve endocarditis. Although the present series did not show a statistically significant advantage to electrode removal over conservative treatment, when analyzed together with pooled data from other studies, it suggests that the surgical approach is preferable.(ABSTRACT TRUNCATED AT 250 WORDS)

Native valve Staphylococcus epidermidis endocarditis: report of seven cases and review of the literature.

This report describes seven patients from three university hospitals whose native valve infective endocarditis was caused by Staphylococcus epidermidis. The literature on endocarditis caused by S. epidermidis is also reviewed and the clinical features of patients with native valve endocarditis due to this organism are compared with those of patients from a general series of infective endocarditis cases. Compared with infective endocarditis caused by other organisms, S. epidermidis endocarditis tends to occur more frequently in male patients. Patients with S. epidermidis endocarditis exhibit fewer embolic complications and skin manifestations. The frequency of congestive heart failure is lower in this group. The relative indolent course and apparent rarity of native valve S. epidermidis endocarditis necessitate a high index of suspicion for early diagnosis.