Factors predictive for delayed enhancement in cardiac resonance imaging in patients undergoing catheter ablation of premature ventricular complexes.

BACKGROUND: Patients undergoing ablation of premature ventricular complexes (PVCs) can have cardiac scar. Risk factors for the presence of scar are not well defined. OBJECTIVES: To determine the prevalence of scarring detected by delayed enhancement cardiac magnetic resonance imaging (DE-CMR) in patients undergoing ablation of PVCs, to create a risk score predictive of scar, and to explore correlations between the scoring system and long-term outcomes. METHODS: DE-CMR imaging was performed in consecutive patients with frequent PVCs referred for ablation. The full sample was used to develop a prediction model for cardiac scar based on demographic and clinical characteristics, and internal validation of the prediction model was done using bootstrap samples. RESULTS: The study consisted of 333 patients (52% male, aged 53.2 ± 14.5 years, preablation ejection fraction 50.9% ± 12.2%, PVC burden 20.7 ± 13.14), of whom 112 (34%) had DE-CMR scarring. Multiple logistic regression analysis showed age (odds ratio [OR] 1.02 [1.01-1.04]/year, P = .019) and preablation ejection fraction (OR 0.92 [0.89-0.94]/%, P < .001) to be predictive of scar. A weighted risk score incorporating age and ejection fraction was used to stratify patients into low-, medium-, and high-risk groups. Scar prevalence was around 86% in the high-risk group and 12% in the low-risk group; high-risk patients had worse survival free of arrhythmia. CONCLUSIONS: Cardiac scar was present in one-third of patients referred for PVC ablation. A weighted risk score based simply on patient age and preprocedural ejection fraction can help discriminate between patients at high and low risk for the presence of cardiac scar and worse arrhythmia outcomes.

Value of mapping and ablation of ventricular tachycardia targets within the coronary venous system in patients with nonischemic cardiomyopathy.

BACKGROUND: Patients with nonischemic cardiomyopathy (NICM) often require epicardial ventricular tachycardia (VT) ablation procedures via subxiphoid access. The coronary venous system (CVS) provides limited access to the epicardial space. OBJECTIVE: The purpose of this study was to determine the value of an approach targeting the CVS in these patients. METHODS: In a series of 41 consecutive patients (mean age 59.7 ± 11.5 years; 36 men [88%]; ejection fraction 34.5% ± 13.1%; 269 inducible VTs [6.6 ± 5.0 VTs per patient]) with NICM and VT, mapping and ablation were performed sequentially at the endocardium, then within the CVS, and finally within the pericardial space if required. RESULTS: VT target sites were identified within the CVS in 15 patients and by subxiphoid access to the pericardial space in 8 patients. Ablation within the CVS eliminated VT inducibility in 9 patients without the need for epicardial ablation. Cardiac magnetic resonance imaging demonstrated that the CVS was closer to a scarred area in patients with CVS-related VT target sites than in other patients (mean 3.5 ± 3.9 mm vs 14.3 ± 8.3 mm; P < .001). A cutoff distance of ≤9 mm from the scar (area under the curve 0.91; 95% confidence interval 0.82-0.99; sensitivity 0.78; specificity 0.93) identified patients with vs patients without VT target sites within the CVS. CONCLUSION: A stepwise approach with mapping/ablation in the endocardium followed by ablation within the CVS can reduce the need for subxiphoid epicardial access in some patients with NICM. Proximity of the scar to the CVS detected by cardiac magnetic resonance imaging can identify the patients most likely to benefit from this approach.

Risk stratification in patients with frequent premature ventricular complexes in the absence of known heart disease.

BACKGROUND: Frequent premature ventricular complexes (PVCs) can be an indicator of structural heart disease. OBJECTIVE: The purpose of this study was to determine the prevalence of scarring detected by delayed enhancement cardiac magnetic resonance (DE-CMR) imaging in patients with frequent PVCs without apparent structural heart disease and to determine the value of programmed ventricular stimulation (PVS) for risk stratification in patients with frequent PVCs and myocardial scarring. METHODS: DE-CMR imaging was performed in patients without apparent heart disease who had frequent PVCs and were referred for ablation. In the presence of scarring, scar volume was measured and correlated with outcome variables. All patients underwent PVS and were monitored for the occurrence of ventricular arrhythmias. Logistic regression was used to compare imaging and procedural findings with long-term outcomes, with adjustment for postablation ejection fraction (EF). RESULTS: The study consisted of 272 patients (135 men; mean age 52 ± 15 years; EF 52% ± 12%). DE-CMR scar was found in 67 patients (25%), and 7 (3%) were found to have inducible ventricular tachycardia (VT). The presence and amount of DE-CMR were related to the risk of long-term VT independent of EF (hazard ratio 18.8 [95% confidence interval] [2.0-176.6], P = .01; and hazard ratio 1.4 [1.1-1.7] per cm3 scar, P <.001, respectively). The positive predictive value and negative predictive value of PVS for VT during long-term follow-up were 71% and 100%, respectively. CONCLUSION: Preprocedural cardiac DE-CMR and PVS can be used to identify patients with frequent PVCs without apparent heart disease who are at risk for VT.