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Interventricular Electrical Delay Introduction The left ventricular (LV) pacing site and the magnitude of the electrical delay within the LV, as expressed by prolonged QRS duration, are major determinants of cardiac resynchronization therapy (CRT) efficacy. We investigated the incremental value of positioning the LV lead in areas of late activation in order to enhance the response to CRT in patients with different degrees of QRS complex lengthening. Methods and Results This analysis was performed on 301 heart failure patients who received a CRT defibrillator. On implantation, the right ventricular (RV)-to-LV interval was measured as the delay between local activations recorded through the RV and LV leads in the final position. After 1 year, 171 (57%) patients displayed reverse LV remodeling, as measured by a ≥15% reduction in the LV end-systolic volume. Both the RV-to-LV interval and its percentage value corrected for the QRS duration were significantly associated with a positive response to CRT. An RV-to-LV interval >80 milliseconds and an RV-to-LV interval/QRS >58% yielded the best prediction of reverse remodeling. Although the response to CRT decreased with shorter QRS duration in the overall population, patients with an RV-to-LV interval >80 milliseconds showed a response rate >65% in all QRS subgroups. Conclusion A longer RV-to-LV interval is associated with reverse LV remodeling after CRT. On implantation attempts could be made to maximize it when selecting the LV lead position, especially in patients with shorter QRS duration, and thus less likely to respond positively to CRT. [ABSTRACT FROM AUTHOR]

Prediction Rule to Identify Patients at High Risk for Early Demise Following CRT Background In patients with advanced heart failure, the decision of whether to pursue cardiac resynchronization therapy (CRT) or to proceed directly to advanced heart failure therapies can be challenging. We sought to create a prediction rule to identify patients with advanced systolic heart failure at heightened risk of rapid deterioration despite receiving CRT. Methods Clinical data were collected on consecutive patients with advanced heart failure presenting for a new CRT device at the Cleveland Clinic between February 12, 2002 and July 8, 2008. Early demise was defined as death, left ventricular assist device, or heart transplant within 6 months following CRT implant. Using a multivariate model, variables associated with early demise were identified and a prediction rule created. Results A total of 879 patients were included of whom 47 met criteria for early demise. Using forward stepwise regression followed by a bootstrapping analysis, the final model included: left ventricular end-diastolic diameter ≥6.5 cm (OR 3.23 [1.72-6.06 g], P < 0.001), the presence of a non-left bundle branch block (non-LBBB) morphology (OR 2.18 [1.18-4.04, P = 0.013]), creatinine ≥1.5 mg/dL (OR 2.98 [1.52-5.49], P < 0.001), and lack of or intolerance to β-blocker use (OR 2.80 [1.46-5.39], P = 0.002). The specificity for ≥2 and ≥3 risk factors was 72.6% and 94.6%, respectively. Conclusions Left ventricular dilatation, the presence of a non-LBBB morphology, renal dysfunction, and lack of or intolerance to β-blockers are associated with early demise following CRT. In patients with at least 3 of these factors, bypassing CRT with early adoption of advanced heart failure therapies may be considered given the high specificity for rapid decline. [ABSTRACT FROM AUTHOR]

Arrhythmia Inducibility Post-AF Ablation Introduction Prior reports demonstrate prognostic value in noninducibility of atrial arrhythmias after atrial fibrillation (AF) ablation and suggest their utility in guiding additional ablation lesion sets. The type and mechanism of induced atrial arrhythmias, their relationship to the underlying atrial substrate, and prognostic significance of induced organized atrial arrhythmias are unknown. Methods and Results One hundred forty-four patients (30 women; median age 60 years; 54% with paroxysmal AF) undergoing AF ablation (circumferential pulmonary vein isolation and focal ablation of nonvein triggers on isoproterenol) were evaluated prospectively. All underwent a standardized postablation induction protocol from the coronary sinus and right atrium: 15 beat burst pacing at 250 milliseconds and decrementing to 180 milliseconds. Sustained rhythms were defined as greater than 2 minutes Of 144 patients, 55 patients (38.2%) did not have sustained inducible arrhythmias. Fifty-two (36.1%) had inducible AF and 37 (25.7%) had inducible organized arrhythmias. A logistic regression analysis showed that age (OR 2.10 per decade; P = 0.003) and hypertension (OR 4.15; P = 0.009) were predictive of inducibility. However, inducibility of either AF or organized arrhythmias was not prognostic of clinical recurrence at 1 year postablation (P = 0.65). Furthermore, inducibility of organized arrhythmias did not predict clinical recurrence of an organized arrhythmia. Only LA size (OR 2.18; 95% CI 1.02-4.67; P = 0.04) and persistent AF (OR 2.43; 95% CI 1.09-5.40; P = 0.03) predicted atrial arrhythmia recurrence. Conclusions Multisite atrial burst pacing post-AF ablation induced organized rhythms in 25.7% and AF in 36.1% of patients after AF ablation. Hypertension and age predict inducibility of arrhythmias, but inducibility did not predict clinical recurrence in follow-up. Distinguishing organized atrial arrhythmias from AF did not yield any further prognostic information. The utility of aggressive stimulation protocols after AF ablation for prognosis and to guide therapy appears limited. [ABSTRACT FROM AUTHOR]

Depression and Cardiac Resynchronization Therapy. Background: The relationship between depression and heart failure is neither coincidental nor trivial, since depression is a powerful predictor of re-hospitalization and mortality. We prospectively studied the prevalence and impact of depression on the clinical outcomes of patients attending for cardiac resynchronization therapy (CRT). We specifically examined whether patients with depression have a different rate of response to CRT and whether CRT has an effect on depressive symptoms. Methods: Sixty-eight recipients of CRT systems were included. The depressive status was evaluated before implant and after 6 months by a structured diagnostic interview measuring Diagnostic and Statistical Manual of Mental Disorders (DSM-IV) criteria of major depression and by a self-report questionnaire (Center for Epidemiological Studies Depression Scale, CES-D). The CRT response was assessed at 6 months by a clinical composite score. Results: At inclusion, DSM-IV criteria of major depression were identified in 41% of the population, while using the self-report questionnaire 65% were observed to have mild to major depressive symptoms (CES-D ≥ 16). Only 4 patients were taking antidepressants. At 6 months, 75% were considered responders to CRT. Response to CRT did not differ between those with and without depression at baseline. The rate of patients with depression at 6 months was significantly lower in responders to CRT compared with nonresponders. Conclusions: We found a high prevalence of depressive symptoms in patients receiving CRT systems. Patients with depression should not be excluded from CRT, because they demonstrate a similar rate of response than the persons without depression and the responders are less likely to be depressed at 6 months. (J Cardiovasc Electrophysiol, Vol. 23, pp. 631-636, June 2012) [ABSTRACT FROM AUTHOR]