BackgroundClinical studies demonstrate that up to 40% of patients do not respond to cardiac resynchronization therapy (CRT), thus, appropriate patient selection is critical to the success of CRT in heart failure.ObjectiveEvaluation of mortality predictors and response to CRT in the Brazilian scenario.MethodsRetrospective cohort study including patients submitted to CRT in a tertiary hospital in southern Brazil from 2008 to 2014. Survival was assessed through a database of the State Department of Health (RS). Predictors of echocardiographic response were evaluated using Poisson regression. Survival analysis was performed by Cox regression and Kaplan Meyer curves. A two-tailed p value less than 0.05 was considered statistically significant.ResultsA total of 170 patients with an average follow-up of 1011 ± 632 days were included. The total mortality was 30%. The independent predictors of mortality were age (hazard ratio [HR] of 1.05, p = 0.027), previous acute myocardial infarction (AMI) (HR of 2.17, p = 0.049) and chronic obstructive pulmonary disease (COPD) (HR of 3.13, p = 0.015). The percentage of biventricular stimulation at 6 months was identified as protective factor of mortality ([HR] 0.97, p = 0.048). The independent predictors associated with the echocardiographic response were absence of mitral insufficiency, presence of left bundle branch block and percentage of biventricular stimulation.ConclusionMortality in patients submitted to CRT in a tertiary hospital was independently associated with age, presence of COPD and previous AMI. The percentage of biventricular pacing evaluated 6 months after resynchronizer implantation was independently associated with improved survival and echocardiographic response.

The content of the text and its data in its form, correctness and reliability are the exclusive responsibility of the author, and do not necessarily represent the official position of Seven Eventos Acadêmicos e Editora. The work may be downloaded and shared as long as credit is given to the author, but without the possibility of altering it in any way or using it for commercial purposes.

Background: First-degree atrioventricular block (AVB) might not be benign. Markedly long PR intervals may cause cardiac dyssynchrony, with many consequences. Restoring optimal AV synchrony represents a reasonable option for hemodynamic and clinical improvement.Objectives: To compare 2 cardiac pacing strategies for bradycardia associated with firstdegree AVB: (1) long PR interval (PRi)-narrow intrinsic QRS, avoiding ventricular pacing but potentially causing AV dyssynchrony (AVD); vs (2) optimized AV interval (oAVi)wide paced QRS, potentially inducing ventricular dyssynchrony.Methodology: Prospective cohort study with patients with permanent DDD pacemakers due to sinus disease associated with first-degree AVB (binodal disease). We analyzed diastolic filling time (DFT), defining 2 groups: patients with AV synchrony (AVS) and AVD. Clinical and echocardiographic follow-up was performed for a year. Results:We studied 43 patients (mean age 71 years; 51.2% female). Longer PRis were associated with worse baseline ventricular systolic function. The AVD group (24/43) showed longer PRi (mean=283.5ms; p≤0.001) and reduced ventricular DFT (p=0.032). Firstdegree AVB with PRi>263ms (relative risk [RR]=1.84; p=0.024; specificity=78.9%; 95% confidence interval [CI] 0.43-0.79) and DFT<40% of the cardiac cycle duration (RR=0.99; p<0.001) were independent predictors of AVD. When PRi>300ms, dyssynchrony was not correctable by AVi optimization. The AVS group (controls, n=19; mean PRi=252.4ms), despite maintaining synchrony, had worsened mitral regurgitation (p=0.008) at follow-up.Conclusions: First-degree AVB comprehends significantly different patients: those with AVD and AVS, determined by DFT and PRi length. In those with AVD, we hypothesized the existence of the "long PR syndrome", defined from a PRi>263ms associated with overt DFT impairment.