Mapping and Ablation of Ventricular Fibrillation Associated With Early Repolarization Syndrome.

BACKGROUND: We conducted a multicenter study to evaluate mapping and ablation of ventricular fibrillation (VF) substrates or VF triggers in early repolarization syndromes (ERS) or J-wave syndrome (JWS). METHODS: We studied 52 patients with ERS (4 women; median age, 35 years) with recurrent VF episodes. Body surface electrocardiographic imaging and endocardial and epicardial electroanatomical mapping of both ventricles were performed during sinus rhythm and VF for localization of triggers, substrates, and drivers. Ablations were performed on VF substrates, defined as areas that had late depolarization abnormalities characterized by low-voltage fractionated late potentials, and VF triggers. RESULTS: Fifty-one of the 52 patients had detailed mapping that revealed 2 phenotypes: group 1 had late depolarization abnormalities predominantly at the right ventricular (RV) epicardium (n=40), and group 2 had no depolarization abnormalities (n=11). Group 1 can be subcategorized into 2 groups: Group 1A included 33 patients with ERS with Brugada electrocardiographic pattern, and group 1B included 7 patients with ERS without Brugada electrocardiographic pattern. Late depolarization areas colocalize with VF driver areas. The anterior RV outflow tract/RV epicardium and the RV inferior epicardium are the major substrate sites for group 1. The Purkinje network is the leading underlying VF trigger in group 2 that had no substrates. Ablations were performed in 43 patients: 31 and 5 group 1 patients had only VF substrate ablation and VF substrates plus VF trigger, respectively (mean, 1.4±0.6 sessions); 6 group 2 patients and 1 patient without group classification had only Purkinje VF trigger ablation (mean, 1.2±0.4 sessions). Ablations were successful in reducing VF recurrences (P<0.0001). After follow-up of 31±26 months, 39 (91%) had no VF recurrences. CONCLUSIONS: There are 2 phenotypes of ERS/J-wave syndrome: one with late depolarization abnormality as the underlying mechanism of high-amplitude J-wave elevation that predominantly resides in the RV outflow tract and RV inferolateral epicardium, serving as an excellent target for ablation, and the other with pure ERS devoid of VF substrates but with VF triggers that are associated with Purkinje sites. Ablation is effective in treating symptomatic patients with ERS/J-wave syndrome with frequent VF episodes.

Proof of concept study of a novel pacemapping algorithm as a basis to guide ablation of ventricular arrhythmias.

Aims: To determine if a software algorithm can use an individualized distance-morphology difference model, built from three initial pacemaps, to prospectively locate the exit site (ES) of ventricular arrhythmias (VA). Methods and results: Consecutive patients undergoing ablation of VA from a single centre were recruited. During mapping, three initial pacing points were collected in the chamber of interest and the navigation algorithm applied to predict the ES, which was corroborated by conventional mapping techniques. Thirty-two patients underwent ES prediction over 35 procedures. Structural heart disease was present in 16 (7 ischaemic cardiomyopathy, 9 non-ischaemic cardiomyopathy), median ejection fraction 45% [Interquartile range (IQR) 26]. The remainder had normal hearts. The navigation algorithm was applied to 46 VA (24 left ventricle, 11 right ventricular outflow tract, 5 left ventricular outflow tract, 4 right ventricle, 2 epicardial) and successfully located the site of best pacemap match in 45 within a median area of 196.5 mm2 (IQR 161.3, range 46.6-1288.2 mm2). Conclusions: In a diverse population of patients with and without structural heart disease, the ES of VA can be accurately and reliably identified to within a clinically useful target area using a simple software navigation algorithm based on pacemapping.

Relationship Between Distance and Change in Surface ECG Morphology During Pacemapping as a Guide to Ablation of Ventricular Arrhythmias: Implications for the Spatial Resolution of Pacemapping.

BACKGROUND: Pacemapping is used to localize the exit site of ventricular arrhythmia. Although the relationship between distance and change in QRS morphology is its basis, this relationship has not been systematically quantified. METHODS AND RESULTS: Patients (n=68) undergoing ventricular arrhythmia ablation between March 2012 and July 2013 were recruited. Pacemapping was targeted to areas of voltage >0.5 mV. Linear mixed-effects models were constructed of distance against morphology difference measured by the root mean square error sum across all 12 ECG leads (E12). Forty of 68 (58%) patients had structural heart disease, and 21/40 (53%) patients were ischemic. Nine hundred thirty-five pacing points were collected, generating 6219 pacing site pair combinations (3087 [50%] ventricular bodies, 756 [12%] outflow tract, and 162 [3%] epicardial). In multivariable analysis, increase in E12 was predicted by increasing distance (0.07 per mm; 95% confidence interval 0.07-0.08; P<0.001). Compared with the left ventricle, E12 values were lower in the right ventricle (P=0.037) and left ventricular outflow tract (P<0.001) and higher in left ventricle-right ventricle pairs (P=0.021) and left ventricular epicardium (P=0.08). There was no difference in E12 in the right ventricular outflow tract compared with the right-left ventricular outflow tract (P=0.75) pairs. Structural heart disease or inadvertent pacing in scar was not associated with changes in E12; however, the presence of latency and split potentials were associated with higher and lower E12 values, respectively (P<0.001). CONCLUSIONS: A robust positive relationship exists between distance and QRS morphological change when restricting pacing points to areas of voltage >0.5 mV. Significant differences in the spatial resolution of pacemapping exist within the heart.

Cardiac sarcoidosis: electrophysiological outcomes on long-term follow-up and the role of the implantable cardioverter-defibrillator.

OBJECTIVES: The objectives of this study were to identify the predictors of life-threatening ventricular arrhythmias in patients with cardiac sarcoidosis (CS) and to evaluate the role of the implantable cardioverter-defibrillator (ICD) in this patient population. BACKGROUND: ICD implantation is a class IIA recommendation for patients with CS. However, some indications for ICD implantation in CS patients are still unclear and not enough data are available to establish predictors of malignant ventricular tachyarrhythmias in this group of patients. METHODS: We retrospectively identified all consecutive patients who were diagnosed with CS, during the period from March 2002 to April 2010. Cardiac rhythm devices were regularly interrogated and clinical data recorded during follow-up visits. RESULTS: Thirty-three patients (17 male) with CS were identified. The mean age was 53 ± 11. The mean left ventricular ejection fraction (LVEF) was 41 ± 18%. Thirty patients received an ICD. Twelve patients (36.3%) had sustained ventricular arrhythmias. Eleven patients received appropriate therapies and 9 patients received inappropriate shocks, representing 36.7% and 30.0% of the ICD population, respectively. Patients who received appropriate ICD therapies were younger with mean age 47.4 ± 7.8, and had a lower mean LVEF 33.0 ± 12.0 compared to those who did not receive ICD therapies (P = 0.0301 and 0.0341, respectively). There were no other demographic, clinical, electrocardiographic, electrophysiological, or imaging markers that predicted the future occurrence of appropriate ICD therapies in our cohort of patients. CONCLUSIONS: CS is strongly associated with malignant ventricular arrhythmias. No specific predictors of such tachyarrhythmias emerged, other than young age and low LVEF.

MRI-Guided ventricular tachycardia ablation: integration of late gadolinium-enhanced 3D scar in patients with implantable cardioverter-defibrillators.

BACKGROUND: Substrate-guided ablation of ventricular tachycardia (VT) in patients with implanted cardioverter-defibrillators (ICDs) relies on voltage mapping to define the scar and border zone. An integrated 3D scar reconstruction from late gadolinium enhancement (LGE) MRI could facilitate VT ablations. METHODS AND RESULTS: Twenty-two patients with ICD underwent contrast-enhanced cardiac MRI with a specific absorption rate of <2.0 W/kg before VT ablation. Device interrogation demonstrated unchanged ICD parameters immediately before, after, or at 68±21 days follow-up (P>0.05). ICD imaging artifacts were most prominent in the anterior wall and allowed full and partial assessment of LGE in 9±4 and 12±3 of 17 segments, respectively. In 14 patients with LGE, a 3D scar model was reconstructed and successfully registered with the clinical mapping system (accuracy, 3.9±1.8 mm). Using receiver operating characteristic curves, bipolar and unipolar voltages of 1.49 and 4.46 mV correlated best with endocardial MRI scar. Scar visualization allowed the elimination of falsely low voltage recordings (suboptimal catheter contact) in 4.1±1.9% of <1.5-mV mapping points. Display of scar border zone allowed identification of excellent pace mapping sites, with only limited voltage mapping in 64% of patients. Viable endocardium of >2 mm resulted in >1.5-mV voltage recordings despite up to 63% transmural midmyocardial scar successfully ablated with MRI guidance. All successful ablation sites demonstrated LGE (transmurality, 68±26%) and were located within 10 mm of transition zones to 0% to 25% scar in 71%. CONCLUSIONS: Contrast-enhanced cardiac MRI can be safely performed in selected patients with ICDs and allows the integration of detailed 3D scar maps into clinical mapping systems, providing supplementary anatomic guidance to facilitate substrate-guided VT ablations.

Integration of three-dimensional scar maps for ventricular tachycardia ablation with positron emission tomography-computed tomography.

OBJECTIVES: This study sought to assess the feasibility of deriving 3-dimensional (3D) scar maps from positron emission tomography (PET)/computed tomography (CT) hybrid imaging and to integrate those into clinical mapping systems to assist in ventricular tachycardia (VT) ablations. BACKGROUND: Ablation strategies for nonidiopathic VT are increasingly based on the anatomic information of the scar and its border zone. However, the current "gold standard" of voltage mapping is limited by its inability to accurately describe a complex 3D scar morphology, its imperfect spatial resolution, and prolonged procedure times. METHODS: Fourteen patients underwent PET/CT multimodality imaging before the VT ablation. We used PET/CT-derived scar maps to characterize myocardial scar using a 17-segment analysis and surface reconstruction. In 10 patients, reconstructed 3D metabolic scar maps were integrated into a clinical mapping system and compared with high-resolution voltage maps. RESULTS: A good correlation was found between the voltage maps and PET/CT-derived scar maps (r = 0.89; r < 0.05). In addition, 3D metabolic scar maps accurately displayed endocardial and epicardial surface and could be successfully integrated with a registration error of 3.7 +/- 0.7 mm. A combination of visual alignment and surface registration was most accurate for myocardial scar accounting for

Relation between left ventricular geometry and transmural dispersion of repolarization.

Studies have shown an association between left ventricular (LV) geometry and complex ventricular ectopic activity. Increased transmural dispersion of repolarization (TDR), which correlates to the interval from the peak to the end of the T wave (Tpe) on the surface electrocardiogram, is linked to ventricular tachyarrhythmias. The relation between LV geometry and TDR is unknown. The mean Tpe interval, measured from leads V(1) to V(3) of the surface electrocardiogram, was assessed in 300 patients (50% men) who had normal LV systolic function and QRS duration and were categorized into 3 equal groups, which were matched by age and gender, according to echocardiographically determined LV geometry (normal structure, concentric remodeling, and LV hypertrophy). The Tpe interval was corrected for the QT interval using Tpe/QTc and was compared among the 3 groups. Compared with those who had normal LV structure, the Tpe interval was significantly prolonged in those who had LV hypertrophy and significantly shortened in those who had concentric remodeling (p = <0.0001 for the 2 comparisons). Correcting for the QT interval using Tpe/QTc yielded similar results. Thus, TDR was increased in patients who had LV hypertrophy but decreased in concentric remodeling compared with those who had normal cardiac structure. Although LV hypertrophy represents a maladaptive geometric process that results in an unfavorable electrical substrate, concentric remodeling may represent a structural adaptation that has a more favorable electrical milieu.