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Introduction: Patients with left ventricular dysfunction (LVD) and LV dyssynchrony may respond to cardiac resynchronization therapy (CRT). However, right ventricular dysfunction (RVD) is a predictor of decreased survival in patients with LVD, and its influence on clinical response to CRT is unknown. The purpose of this study was to examine the effect of RVD on the clinical response to CRT., Methods and Results: A retrospective cohort of consecutive patients who underwent implantation of a CRT implantable cardioverter-defibrillator (ICD) were included and deemed to have RVD based on a RV ejection fraction <0.40. A lack of response to CRT was defined as: death, heart transplantation, implantation of an LV assist device, absent improvement in NYHA functional class at 6 months or hospice care. Among 130 patients included (mean age 58 +/- 11 years, 68.5% male, 87.7% Caucasian, 51.5% nonischemic cardiomyopathy), 77 (59.2%) had no response to CRT as defined above. Of the nonresponders, 43 (56%) had RVD and 34 (44%) did not have RVD (P = 0.02). After adjustment for age, race, gender, cardiomyopathy type, atrial fibrillation, serum sodium, and severe mitral regurgitation, RVD (adjusted OR = 0.34, 95%CI 0.14-0.82), female gender (adjusted OR = 0.36, 95%CI 0.14-0.95), and serum creatinine (adjusted OR = 0.25, 95%CI 0.09-0.71) were independently associated with decreased odds of response to CRT. There was a significant difference in survival of patients with and without RVD after CRT (log rank P = 0.01)., Conclusion: RVD represents a strong predictor of lack of clinical response to CRT in patients with CHF due to LVD and should be considered when prescribing CRT.

Introduction: Idiopathic ventricular arrhythmias (VAs) can originate from the left ventricular (LV) papillary muscles (PAMs). This study investigated the prevalence, electrocardiographic and electrophysiological characteristics, and results of catheter ablation of these VAs, and compared them with other LV VAs., Methods and Results: We studied 71 patients with VAs originating from the LV anterolateral and posteroseptal regions among 159 patients undergoing successful catheter ablation of idiopathic LV VAs. PAM VAs were uncommon, rare in a sustained form, and more common from the posterior papillary muscle (PPM) than anterior papillary muscle (APM). A younger age was a good predictor for differentiating left posterior fascicular VAs from PPM VAs. There were several electrocardiographic features that accurately differentiated PAM and LV fascicular VAs from mitral annular VAs. However, an R/S ratio < or =1 in lead V6 in the LV anterolateral region and a QRS duration >160 ms in the LV posteroseptal region were the only reliable predictors for differentiating PAM VAs from LV fascicular VAs. A sharp ventricular prepotential was recorded at the successful ablation site during 42% of the PAM VAs. Radiofrequency current with an irrigated or conventional 8-mm tip ablation catheter was required to achieve a lasting ablation of the PAM VA origins whereas that with a nonirrigated 4-mm tip ablation catheter produced excellent results in LV fascicular and mitral annular VAs., Conclusions: There are differences in the electrocardiographic and electrophysiological features among VAs originating from these regions that are helpful for their diagnosis and effective catheter ablation.