Left atrial volume predicts atrial fibrillation recurrence after radiofrequency ablation: a meta-analysis.

Aims: Left atrial (LA) diameter is a predictor of atrial fibrillation (AF) recurrence following radiofrequency catheter ablation (RFA). However, LA volume (LAV) is more accurate in assessing LA size. Studies evaluating LAV as a predictor of AF recurrence are contradictory; therefore, we performed a meta-analysis to assess whether LAV is an independent predictor of AF recurrence following RFA. Methods and results: All studies reporting LAV/LAV index (LAVi) as a predictor of AF recurrence following RFA were included. For studies reporting mean LAV/ LAVi in patients with and without AF recurrence, standard difference in means (SDM) and standard errors were calculated, and combined using meta-analytical techniques. For studies reporting adjusted odds ratio (OR) for AF recurrence based on LAV/LAVi, log ORs were combined using generic inverse variance. Twenty one studies (3822 subjects) were included. Meta-analysis of 11 studies (1559 subjects) reporting LAV, showed that patients with AF recurrence had a higher mean LA volume compared to patients with no recurrence (SDM 0.801; CI 0.387-1.216). Data from 9 studies (1425 subjects) comparing LAVi showed that, patients with AF recurrence had a higher mean LAVi compared to patients with no recurrence (SDM-0.596; CI 0.305-0.888). Thirteen studies (2886 patients) reporting ORs for AF recurrence based on LAV/ LAVi, showed that LAV/LAVi was independently predictive of AF recurrence post-RFA (OR-1.032, CI- 1.012-1.052). Conclusions: Patients with AF recurrence following RFA have a higher mean LAV/LAVi compared to patients with no recurrence. Large LAV/LAVi increases the odds of AF recurrence post RFA.

Routine DFT testing in patients undergoing ICD implantation does not improve mortality: A systematic review and meta-analysis.

Defibrillation threshold (DFT) testing has been an integral part of implantable cardioverter-defibrillator (ICD) implantation to confirm appropriate sensing of ventricular fibrillation and to establish an adequate safety margin for defibrillation. However, there is a lack of evidence regarding benefits of routine DFT testing. Therefore, we performed a meta-analysis to assess its mortality benefit. We searched MEDLINE for studies comparing mortality outcomes in ICD recipients who underwent DFT testing to those who did not. For the second analysis, studies comparing outcomes in patients with high- vs low-energy DFT were included. Odds ratio and standard errors were calculated, and inverse variance method in a random-effect model was used to combine effect sizes. Fifteen studies with 10,975 subjects comparing outcomes in patients who underwent routine DFT testing during ICD implantation and those who did not were included. There was no difference in the group that did not undergo DFT testing with regards to all-cause mortality (OR 0.935; CI 0.725-1.207; P = 0.606), cardiac mortality (OR 0.709; CI 0.385-1.307; P = 0.271), noncardiac mortality (OR 0.921; CI 0.701-1.210; P = 0.554), and arrhythmic mortality (OR 1.152; CI 0.831-1.596; P = 0.396). Percentage of successful appropriate first shocks among the two groups showed no difference. Five studies with 2278 subjects were included in the second analysis comparing patients with low DFT vs high DFT. Patients with high DFT had no significant increase in all-cause mortality compared to patients with low DFT (OR 0.527; CI 0.034-8.107; P = 0.646). Patients requiring higher DFT had no increased all-cause mortality compared to patients with lower DFT. Routine DFT testing during ICD implantation does not confer any significant benefit.

Cardiac Resynchronization Therapy May Be Antiarrhythmic Particularly in Responders: A Systematic Review and Meta-Analysis.

OBJECTIVES: This study sought to study the effect of echocardiographic response to cardiac resynchronization therapy (CRT) on ventricular arrhythmias (VA). The effect of CRT-defibrillator on sustained VA was compared with implantable cardioverter-defibrillator (ICD)-only therapy. BACKGROUND: CRT is an effective adjunctive therapy in selected patients with advanced congestive heart failure, but its effect on VA remains controversial. METHODS: PubMed was searched to identify studies. For primary comparison, studies reporting incidence of VA in patients with congestive heart failure with CRT compared with ICD were included. For secondary comparison, studies reporting incidence of VA in echocardiographic responders compared with nonresponders were included. Studies reporting incidence of VA in CRT nonresponders before and after CRT upgrade from ICD were assessed for the third comparison. Inverse variance method in a random-effects model was used to combine effect sizes. RESULTS: Thirteen studies (4,631 subjects) were included in the primary meta-analysis. Patients with CRT had a significantly lower incidence of VA compared with patients with ICD only (odds ratio: 0.754; confidence interval: 0.594 to 0.959). Thirteen studies (n = 3,667) were included in the meta-analysis of VA in CRT responders versus nonresponders. Responders had a significantly lower risk of VA (odds ratio: 0.436; confidence interval: 0.323 to 0.589). Multivariate meta-regression showed that the percentage beta-blocker use and follow-up duration explained heterogeneity between the studies. Three studies were included in the comparison of VA in CRT nonresponders before and after upgrade from ICD. CRT nonresponders had an elevated risk of VA compared with ICD-only subjects (odds ratio: 1.497; confidence interval: 1.225 to 1.829). CONCLUSIONS: CRT may significantly reduce risk of VA compared with ICDs in patients who meet criteria for CRT. CRT responders have significant reduction in VA compared with nonresponders. CRT nonresponse might significantly increase risk of VA.