Echocardiographic parameters to predict inadequate defibrillation safety margin in patients receiving implantable cardioverter defibrillators for primary prevention.

BACKGROUND: Implantable cardioverter defibrillators (ICDs) have become an important part of the management of patients with congestive heart failure. At the time of ICD implantation, ventricular fibrillation (VF) is induced to assess adequate energy required for defibrillation. There are multiple parameters which influence the defibrillation safety margin (DSM); however, these factors are not well-established when ICDs are implanted for the primary prevention of sudden cardiac death (SCD) in patients with severe systolic dysfunction. We evaluated multiple clinical and echocardiographic parameters as predictors of adequate DSM in patients referred for ICD implantation for the primary prevention of SCD. METHODS: We prospectively enrolled 41 patients for ICD implantation with clinical indications for the primary prevention of SCD. Two blinded independent readers evaluated the prespecified echocardiographic parameters. These included left ventricular (LV) mass, indices of right ventricular and LV systolic and diastolic functions, and LV geometric dimensions. Basic clinical demographics, including age, gender, comorbidities, and etiology of cardiomyopathy, were also evaluated. DSM was established using our standard protocol for defibrillation testing which includes VF with successful first shock terminating VF at a value at least 10 J below the maximum output of the implanted device. High defibrillation thresholds (DFT) were defined as >21 J. RESULTS: The mean age is 61.8 ± 14.7 years, with men comprising the majority of the patients (73 %). The only clinical variables which predicted the high DFT were age (in years) (54.5 ± 17.5 vs. 65.7 ± 11.3, p = 0.044), QRS duration (in milliseconds) (116.0 ± 29.5 vs. 110.5 ± 21.8, p = 0.03), LV mass (in grams) (241.0 ± 77.9 vs. 181.9 ± 52.3, p = 0.006), and LV mass index (in grams per square meter) (111.1 ± 38.2 vs. 86.4 ± 21.1, p = 0.02). On multivariate logistic regression analysis, LV mass was the only independent predictor of low DFT (≤22 J) in patients with ICD implanted for the primary prevention of SCD. CONCLUSION: LV mass may help predict an adequate DSM in patients who are referred for ICD implantation for the primary prevention of SCD. These results may help distinguish the patients who may require high-energy devices prior to the implantation procedure. These results may help distinguish patients requiring high-energy devices, coils, or advanced programming prior to implantation and appropriate referral to electrophysiologists.

Valvular perforation in left-sided native valve infective endocarditis.

BACKGROUND: Left-sided native valve infective endocarditis (LNVIE) can result in mitral (MP) and aortic (AP) valve perforation, the prognostic significance of which remains poorly defined. HYPOTHESIS: Valvular perforation is associated with worse outcomes. METHODS: Retrospective review of patients with LNVIE during 1998-2005 was performed to examine characteristics and outcome predictors of LNVIE complicated by valve perforation. Patients were stratified as: group A: MP or AP detected by transesophageal echocardiography (TEE) or surgery; group B: no TEE evidence of MP or AP. RESULTS: A total of 123 patients were included (group A = 47, group B = 76). In group A, 35 patients (74.5%) had MP alone, 11 (23.4%) had AP alone, and 1 patient had both. Severe valvular insufficiency was encountered more in group A (85.1% versus 59.2%, p = 0.003), so was hemodialysis (40.4% versus 17.1%, p = 0.004) and indications for valvular surgery (93.6% versus 77.6%, p = 0.02). Group A had a higher rate of in-hospital death (31.9% versus 15.8%, p = 0.04). Among patients who had an indication for valvular surgery, the in-hospital mortality rate for those who underwent valvular surgery was 16.7% in group A, and 7.9% in group B (p = 0.4), compared to those who did not undergo surgery (71.4% versus 33.3%, p = 0.04). Amongst survivors, hospital stay was on average 9.2 d longer in group A (38.9 versus 29.7 d, p = 0.05). Univariate analysis revealed association between lower survival and valvular perforation (odds ratio [OR]: 0.4, 95% confidence interval [CI]: 0.17-0.95), that was lost after adjusting for hemodialysis. CONCLUSIONS: Valve perforation complicating LNVIE is associated with hemodialysis, severe valvular insufficiency, and significant morbidity and mortality. Compared to conservative management, early surgical intervention is associated with improved survival.

Factors determining extreme brain natriuretic peptide elevation.

Brain natriuretic peptide (BNP) level is elevated in heart failure and reflects its severity. It is unknown why some patients have extremely high BNP levels. The authors retrospectively reviewed data on 179 consecutive patients whose BNP levels fell within one of several predetermined ranges: mild elevation, 500 to 1000 pg/mL (n=82); moderate elevation, 2000 to 3000 pg/mL (n=48); and high elevation, 4000 to 20,000 pg/mL (n=49). The statistical analysis was conducted with the unpaired t test and Pearson's correlation coefficient. Adjustments were made for age, sex, and serum creatinine level. Patients with moderate BNP elevation were more symptomatic and had more advanced structural and hemodynamic changes than did patients with lower BNP elevation. Characteristics of the high BNP level group did not differ from those of the moderate BNP level group. Serum creatinine level correlated with BNP level, but neither age nor sex did. High BNP level (4000-20,000 pg/mL) is determined more by renal dysfunction than by the severity of heart failure.