UltraSOUND-based Characterization of Ventricular Tachycardia SCAR and Arrhythmogenic Substrate: the SOUNDSCAR Study

BACKGROUND Intracardiac echocardiography (ICE) represents a valuable image integration technique, with the unique advantage of dynamic real-time scar characterization. OBJECTIVES The goals of this study were to assess the correlation between ICE-defined and electroanatomic mapping (EAM)-defined scar in patients with ischemic cardiomyopathy and to define the outcomes of ICE-guided ventricular tachycardia (VT) ablation. METHODS Thirty-eight patients with ischemic cardiomyopathy (SOUNDSCAR cohort) underwent full left ventricular (LV) ICE imaging and EAM. ICE-defined scar parameters (end-diastolic and end-systolic wall diameter [EDWD and ESWD], end systolic wall thickening [percentage difference between EDWD and ESWD with respect to EDWD], slope [end-diastole to end-systole wall thickening], and American Heart Association wall motion scoring) were correlated with EAM-defined scar (voltage <1.5 mV). In a separate cohort (n = 21), outcomes of an ICE-guided VT ablation approach (EAM focused to ICE defined scar regions) were compared with those of conventional ablation (full left ventricular mapping with EAM only; n = 21). RESULTS In the 38 SOUNDSCAR patients (mean age 67 +/- 11 years; 35 male [92%]; left ventricular ejection fraction 31% +/- 10%; 2474 ICE segments; 524 ICE sectors), all ICE-defined parameters strongly predicted EAM-defined scar (area under the curve: American Heart Association score 0.873; ESWD 0.880; EDWD 0.827; slope 0.855; percentage difference between EDWD and ESWD with respect to EDWD, 0.851). All ICE-defined parameters had large effect sizes for predicting EAM-defined scar (logistic regression, P < .001). A detailed topographical comparison of ICE-defined (slope) and EAM-defined scar was possible in 25 patients and demonstrated 88% +/- 10% overlap. Compared with conventional VT ablation, ICE-guided ablation was associated with shorter procedure times and comparable VT-free survival (ICE-guided vs conventional: procedure time 240 +/- 20 minutes vs 298 +/- 39 minutes; P < .001; VT recurrence 3 [14%] vs 7 [31%]; P = .19). CONCLUSION ICE-defined scar demonstrates a strong correlation with EAM-defined scar. ICE-guided VT ablation is associated with enhanced procedural efficiency.