Echocardiographic predictors of survival in patients undergoing radiofrequency ablation of postinfarct clinical ventricular tachycardia

Prognostic importance of wall motion abnormalities in patients with ischemic cardiomyopathy and an implantable cardioverter-defibrillator

Patients with extensive regional wall motion abnormalities are predisposed to development of ventricular tachyarrhythmia. The prognostic effect of this in patients with an implantable cardioverter-defibrillator (ICD) and coronary artery disease (CAD) is not known. Echocardiographic left ventricular systolic indexes, wall motion score index (WMSI), and extent of regional akinesia in 140 patients (65 +/- 10 years old; 92% men) with an ICD and CAD were studied. Arrhythmic events requiring ICD therapy and causing death (n = 41, 29%) were recorded over a mean follow-up of 1.4 +/- 0.8 years. Left ventricular basal fractional shortening, ejection fraction, global WMSI, and extent of akinesia, especially in the inferoposterior regions of a right coronary artery territory, were univariate predictors (all p values <0.05). Global WMSI (hazard ratio 2.18, 95% confidence interval 1.03 to 4.65, p = 0.04) and fractional shortening (hazard ratio 0.93, 95% confidence interval 0.88 to 1.00, p = 0.04) were multivariate predictors. Global WMSI (p = 0.04) and > or =2 right coronary region akinetic segments (p = 0.05) provided incremental risk prediction to left ventricular ejection fraction in a global risk-assessment model (chi-square p = 0.001). Presence of right coronary region akinesia better identified those at increased risk of events (p = 0.02) compared with the presence of left anterior descending region akinesia (p = 0.2), independent of systolic function. In conclusion, global WMSI and left ventricular basal fractional shortening were important additional risk predictors of ICD events in CAD. Global WMSI and right coronary region inferoposterior akinesia provided independent and incremental risk assessment to left ventricular ejection fraction and improved identification of those at increased risk of ICD-related events in patients with ischemic cardiomyopathy.

QTL mapping in a mouse model of cardiomyopathy reveals an ancestral modifier allele affecting heart function and survival

The progression from myocardial hypertrophy to heart failure is a complex process, involving genetic and environmental factors. Elucidating the genetic components contributing to heart failure has been difficult, largely because of the heterogeneity of human populations. We have employed a strategy to map genetic loci that modify the heart failure phenotype in a transgenic mouse model of cardiomyopathy caused by cardiac-specific overexpression of calsequestrin. Strain-specific differences in both cardiac function and survival are observed when the transgene is moved into different inbred mouse strains. We have previously reported linkage results from mapping in reciprocal backcrosses between C57/BL6 (BL6) and DBA/2J (DBA) and a backcross between DBA/AKR and AKR. Here we report the results of a genome-wide linkage scan in the reciprocal backcross between DBA/AKR and DBA. We identified one novel locus on Chromosome (Chr) 18 that affects heart function and a second on Chr 3 that shows significant linkage to both survival and heart function. Intriguingly, the Chr 3 allele of AKR shows a susceptibility effect on phenotype, whereas the overall effect of the AKR genetic background is protective. The Chr 3 locus also completely overlaps the Hrtfm2 locus, which was previously mapped in crosses between DBA and BL6. Mapping the same QTL in two different crosses allowed us to use ancestral haplotypes to narrow the candidate gene interval from 9 to 2 Mb. Identification of the genes at these QTLs in the mouse will provide novel candidate genes that can be evaluated for their role in human heart failure.

Clinical results with catheter ablation: AV junction, atrial fibrillation and ventricular tachycardia

With the limitations of pharmacologic and device therapies for atrial fibrillation and ventricular tachycardia, catheter ablation is assuming a larger role in the management of patients with these common arrhythmias. Multiple case series and clinical trials have helped to define the evolving role of these techniques for ablation of the atrioventricular node, atrial fibrillation, and ischemic ventricular tachycardia. Based on very low complication rates, excellent efficacy and proven outcomes with radiofrequency ablation of the atrioventricular node, this approach with permanent pacing should play a larger role in the treatment of symptomatic patients with permanent atrial fibrillation. While linear ablation of atrial fibrillation has limited clinical utility for the treatment of this common arrhythmia, the results of multiple case series of focal atrial fibrillation ablation indicate the potential for an expanding role of this curative technique. Catheter ablation techniques for ventricular tachycardia in the setting of coronary artery disease have a role as supplemental therapy to the implantable cardioverter defibrillator in patients with recurrent pharmacologically refractory ventricular arrhythmias requiring frequent device interventions.