Jagdesh Kandala

QRS morphology, left ventricular lead location, and clinical outcome in patients receiving cardiac resynchronization therapy.

AIMS Several studies have reported a poor outcome with cardiac resynchronization therapy (CRT) in non-left bundle branch block (LBBB) patients. Although the left ventricular (LV) lead location is an important determinant of the clinical outcome, there is scant information regarding its role in non-LBBB patients. This study sought to examine the impact of electrical and anatomical location of the LV lead in relation to baseline QRS morphology on the CRT outcome. METHODS AND RESULTS A left ventricular lead electrical delay (LVLED) was measured intra-procedurally as an interval between QRS onset on the surface electrocardiogram (ECG) to the peak of sensed electrogram on LV lead and corrected for QRS width. The impact of the LVLED on time to first heart failure hospitalization (HFH), and composite outcome of all-cause mortality, HFH, LVAD implantation, and cardiac transplantation at 3 years was assessed. Among 144 patients (age 67 ± 12 years, QRS duration 156 ± 28 ms, non-LBBB 43%), HFH was higher in non-LBBB compared with LBBB (43.5 vs. 24%, P = 0.015). Within LBBB, patients with the long LVLED (≥50%) had 17% HFH vs. 53% in the short LVLED (<50%), P = 0.002. Likewise in non-LBBB, patients with the long LVLED compared with the short LVLED had a lower HFH (36 vs. 61%, P = 0.026). In adjusted Cox proportional hazards model, the long LVLED in LBBB and non-LBBB was associated with an improved outcome. Specifically, in non-LBBB, LVLED ≥50% was associated with improved event-free survival with respect to time to first HFH (HR: 0.34; P = 0.011) and composite outcome (HR: 0.41; P = 0.019). CONCLUSION Cardiac resynchronization therapy delivered from an LV pacing site characterized by the long LVLED was associated with the favourable outcome in LBBB and non-LBBB patients.

Non-pharmacological modulation of the autonomic tone to treat heart failure

The autonomic nervous system has a significant role in the pathophysiology and progression of heart failure. The absence of any recent breakthrough advances in the medical therapy of heart failure has led to the evolution of innovative non-pharmacological interventions that can favourably modulate the cardiac autonomic tone. Several new therapeutic modalities that may act at different levels of the autonomic nervous system are being investigated for their role in the treatment of heart failure. The current review examines the role of renal denervation, vagal nerve stimulators, carotid baroreceptors, and spinal cord stimulators in the treatment of heart failure.

Clinical, Laboratory, and Pacing Predictors of CRT Response

A decade of research has established the role of cardiac resynchronization therapy (CRT) in medically refractory, moderate to severe systolic heart failure (HF) with intraventricular conduction delay. CRT is an electrical therapy instituted to reestablish ventricular synchronization in order to improve cardiac function and favorably modulate the neurohormonal system. CRT confers a mortality benefit, improved HF hospitalizations, and functional outcome in this population, but not all patients consistently demonstrate a positive CRT response. The nonresponder rate varies from 20% to 40%, depending on the defined response criteria. Efforts to improve response to CRT have focused on a number of fronts. Methods to optimize the correction of electrical and mechanical dyssynchrony, which is the primary target of CRT, has been the focus of research, in addition to improving patient selection and optimizing post-implant care. However, a major issue in dealing with improving nonresponse rates has been finding an accurate and generally accepted definition of “response” itself. The availability of a standard consensus definition of CRT response would enable the estimation of nonresponder burden accurately and permit the development of strategies to improve CRT response. In this review, we define various aspects of “response” to CRT and outline variability in the definition criteria and the problems with its inconsistencies. We describe clinical, laboratory, and pacing predictors that influence CRT response and outcome and how to optimize response.

Impact of myocardial viability and left ventricular lead location on clinical outcome in cardiac resynchronization therapy recipients with ischemic cardiomyopathy.

Cardiac resynchronization therapy (CRT) recipients with ischemic cardiomyopathy (ICM) have scar segments that may limit ventricular resynchronization and clinical response. The impact of myocardial viability at the left ventricular (LV) pacing site on CRT response is poorly elucidated.

Assessing mitral regurgitation in the prediction of clinical outcome after cardiac resynchronization therapy.

BACKGROUND Cardiac resynchronization therapy (CRT) has been shown to reduce mitral regurgitation (MR), although the clinical impact of this improvement remains uncertain. OBJECTIVES We sought to evaluate the impact of MR improvement on clinical outcome after CRT and to assess predictors and mechanism for change in MR. METHODS This was a cohort study of patients undergoing CRT for conventional indications with baseline and follow-up echocardiography (at 6 months). MR severity was classified into 4 grades. The primary end point was time to all-cause death or time to first heart failure (HF) hospitalization assessed at 3 years. RESULTS A total of 439 patients were included: median age was 70.2 years, 90 (20.5%) were women, 255 (58.1%) with ischemic cardiomyopathy, and mean QRS width was 162 ms. Worsening severity of baseline MR was independently predictive of HF or all-cause mortality (hazard ratio 1.33; 95% confidence interval 1.01-1.75; P = .042). Reduction in MR after CRT was significantly associated with lower HF hospitalization and improved survival (hazard ratio 0.65; 95% confidence interval 0.49-0.85; P = .002). Degree of baseline MR and longer surface QRS to left ventricular lead time were significant predictors of MR change. Patients with MR reduction exhibited lower mitral valve tenting area (P < .001) and coaptation height (P < .001) than those with stable or worsening MR, suggestive of improved ventricular geometry as a mechanism for change in MR. CONCLUSION Degree of baseline MR and change in MR after CRT predicted all-cause mortality and HF hospitalization at 3 years. Longer surface QRS to left ventricular lead time at implant may be a means to target MR improvement.

Electrical delay in apically positioned left ventricular leads and clinical outcome after cardiac resynchronization therapy.

Electrical Delay in Apically Positioned LV Leads. Introduction: In recent studies, an anatomical apical left ventricular (LV) lead pacing location has been associated with deleterious outcome after cardiac resynchronization therapy (CRT). The differential impact of the LV lead electrical location in these patients remains unknown.

Renal Response in Patients with Chronic Kidney Disease Predicts Outcome Following Cardiac Resynchronization Therapy.

Chronic kidney disease (CKD) severity is associated with increased morbidity and mortality in congestive heart failure. There is a paucity of data regarding renal improvement after cardiac resynchronization therapy (CRT) and its potential impact on clinical outcomes, especially in patients with severe CKD.

Does Prior Valve Surgery Change Outcome in Patients Treated with Cardiac Resynchronization Therapy

Cardiac valve surgery (CVS) has been implicated as a potential barrier to optimal response after cardiac resynchronization therapy (CRT) though prospective data regarding outcome remains limited. We sought to determine CRT response in patients with a prior history of CVS.

STEM CELL THERAPY IN CHRONIC ISCHEMIC CARDIOMYOPATHY: A META-ANALYSIS

Results: Of 226 reports identified, 9 RCTs (n = 467 patients; average LVEF at baseline 32 ± 7%) were included. Based on a random effects model, BMSCT improved LVEF by 4.27% (95% CI 2.13 to 6.41, p = 0.0001) at 6 months (see Figure), with greater improvement seen in IM vs. IC infusion (5.43% [95% CI 3.65 to 7.21], p < 0.0001 vs. 0.17% [95% CI -5.32 to 5.66], p=NS). Overall, LVESV decreased by -18.1 mL (95% CI -34.9 to -1.25, p = 0.04) and LVEDV decreased by -16.42 mL (95% CI -30.80 to -2.04, p=0.03).

ANGIOGRAPHIC AND NUCLEAR IMAGING PREDICTORS OF RESPONSE TO CARDIAC RESYNCHRONIZATION THERAPY (CRT) IN ISCHEMIC CARDIOMYOPATHY

Although scar has been associated with poor outcome after CRT, the impact of coronary artery disease (CAD) severity or ischemia on CRT response remains uncertain. A prospective cohort of CRT patients with ischemic cardiomyopathy was evaluated for ischemia and scar with nuclear perfusion imaging.