Mathew D. Hutchinson

Electroanatomic Substrate and Ablation Outcome for Suspected Epicardial Ventricular Tachycardia in Left Ventricular Nonischemic Cardiomyopathy

OBJECTIVES The aim of the study was to define the epicardial substrate and ablation outcome in patients with left ventricular nonischemic cardiomyopathy (NICM) and suspected epicardial ventricular tachycardia (VT). BACKGROUND Ventricular tachycardia in NICM often originates from the epicardium. METHODS Twenty-two patients with NICM underwent detailed endocardial and epicardial bipolar voltage maps and VT ablation for suspected epicardial VT. Eight patients with normal hearts and idiopathic VT served to define normal epicardial electrograms. Low-voltage regions were also assessed for wide (>80 ms), split, or late electrograms. RESULTS Normal epicardial bipolar voltage was identified as >1.0 mV on the basis of the reference population. Confluent low-voltage areas were present in 18 epicardial (82%) and 12 endocardial (54%) maps and were typically over basal lateral LV. In the 18 patients with epicardial VT on the basis of activation/pacemapping, the mean epicardial area was greater than the endocardial low-voltage area (55.3 +/- 33.5 cm(2) vs. 22.9 +/- 32.4 cm(2), p < 0.01). Epicardial low-voltage areas showed 49.7% wide (>80 ms), split, and/or late electrograms rarely seen in the reference patients (2.3%). During follow-up of 18 +/- 7 months, ablation resulted in VT elimination in 15 of 21 patients (71%) including 14 of 18 patients (78%) with epicardial VT. CONCLUSIONS In patients with NICM and VT of epicardial origin, the substrate is characterized by areas of basal LV epicardial > endocardial bipolar low voltage. The electrograms in these areas are not only small (<1.0 mV) but wide (>80 ms), split, and/or late, and help identify the substrate targeted for successful ablation.

Endocardial unipolar voltage mapping to detect epicardial ventricular tachycardia substrate in patients with nonischemic left ventricular cardiomyopathy

Background—Patients with nonischemic left ventricular cardiomyopathy (LVCM) and ventricular tachycardia (VT) have complex 3-dimensional substrate with variable involvement of the endocardium (ENDO) and epicardium (EPI). The purpose of this study was to determine whether ENDO unipolar (UNI) mapping with a larger electric field of view could identify EPI low bipolar (BIP) voltage regions in patients with LVCM undergoing VT ablation. Methods and Results—The reference value for normal ENDO unipolar voltage was determined from 6 patients without structural heart disease. Consecutive patients undergoing VT ablation over an 8-year period with detailed (>100 points) LV ENDO and EPI mapping and normal LV ENDO BIP voltage were identified. From this cohort, we compared patients with structurally normal hearts and normal EPI BIP voltage (EPI−, group 1) with patients with LVCM and low LV EPI BIP voltage regions present (EPI+, group 2). Confluent regions of ENDO UNI and EPI BIP low voltage (>2 cm2) were measured. The normal signal amplitude was >8.27 mV for LV ENDO UNI electrograms. Detailed LV ENDO-EPI maps in 5 EPI− patients were compared with 11 EPI+ patients. Confluent ENDO UNI low-voltage regions were seen in 9 of 11 (82%) of the EPI+ (group 2) patients compared with none of 5 EPI− (group 1) patients (P<0.001). In all 9 patients with ENDO UNI low voltage, the ENDO UNI low-voltage regions were directly opposite to an area of EPI BIP low voltage (61% ENDO UNI-EPI BIP low-voltage area overlap). Conclusions—EPI arrhythmia substrate can be reliably identified in most patients with LVCM using ENDO UNI voltage mapping in the absence of ENDO BIP abnormalities.

Endocardial unipolar voltage mapping to identify epicardial substrate in arrhythmogenic right ventricular cardiomyopathy/dysplasia

BACKGROUND The risk and success of epicardial substrate ablation for ventricular tachycardia (VT) support the value of techniques identifying the epicardial substrate with endocardial mapping. OBJECTIVE The purpose of this study was to test the hypothesis that endocardial unipolar voltage mapping in patients with right ventricular (RV) VT and preserved endocardial bipolar voltage abnormalities might identify the extent of epicardial bipolar voltage abnormality. METHODS Using a cutoff of < 5.5 mV for normal endocardial unipolar voltage derived from 8 control patients without structural heart disease, 10 patients with known ARVC/D (group 1, retrospective) and 13 patients with RV VT (group 2, prospective) with modest or no endocardial bipolar voltage abnormalities underwent detailed endocardial and epicardial mapping. RESULTS The area of epicardial unipolar voltage abnormality in all 10 group 1 patients with ARVC/D (62 ± 21 cm²) and in 9 of the 13 group 2 patients (8 with criteria for ARVC/D) (53 ± 21 cm²) was on average three times more extensive than the endocardial bipolar abnormality and correlated (r = 0.63, P <.05 and r = 0.81, P <.008, respectively) with the larger area epicardial bipolar abnormality with respect to size (group 1: 82 ± 22 cm²; group 2: 68 ± 41 cm²) and location. In the remaining 4 group 2 patients and 3 additional reference patients without structural heart disease, endocardial bipolar, endocardial unipolar, and, as predicted, epicardial bipolar voltage all were normal. CONCLUSION Endocardial unipolar mapping with cutoff of 5.5 mV identifies more extensive areas of epicardial bipolar signal abnormalities in patients with ARVC/D and limited endocardial VT substrate.

Long‐Term Clinical Efficacy and Risk of Catheter Ablation for Atrial Fibrillation in the Elderly

Introduction: The number of elderly patients with atrial fibrillation (AF) is increasing rapidly, and the safety and efficacy of catheter ablation in this demographic group has not been established.

Reversal of outflow tract ventricular premature depolarization–induced cardiomyopathy with ablation: Effect of residual arrhythmia burden and preexisting cardiomyopathy on outcome

BACKGROUND Outflow tract ventricular premature depolarizations (VPDs) can be associated with reversible left ventricular cardiomyopathy (LVCM). Limited data exist regarding the outcome after ablation of outflow tract VPDs from the LV and the impact of residual VPDs or preexisting LVCM prior to the diagnosis of VPDs on recovery of LV function. OBJECTIVE To examine the safety, efficacy, and long-term effect of radiofrequency ablation on LV function in patients with LVCM and frequent outflow tract VPDs and examine the effect of ablation in patients with LVCM known to precede the onset of VPDs and the impact of residual VPD frequency on recovery of LV function. METHODS Sixty-nine patients (43 men; age 51 ± 16 years) with nonischemic LVCM (left ventricular ejection fraction [LVEF] 35% ± 9%, left ventricular diastolic diameter [LVDD] 5.8 ± 0.7 cm) were referred for ablation of frequent outflow tract VPDs (29% ± 13%). RESULTS VPDs originated in the right ventricular outflow tract in 27 (39%) patients and the left ventricular outflow tract in 42 (61%) patients. After follow-up of 11 ± 6 months, 44 (66%) patients had rare (<2%) VPDs, 15 (22%) had decreased VPD burden (>80% reduction and always <5000 VPDs), and 8 (12%) had no clinical improvement with persistent (5 patients) or recurrent (3 patients) VPDs. Only patients with either rare or decreased VPD burden had a significant improvement in LVEF (ΔLVEF 14% ± 9% vs 13% ± 7% vs -3% ± 6%, respectively, P <.001) and LVDD (ΔLVDD -4 ± 5 vs -2 ± 4 vs 0 ± 4, respectively, P = .038), regardless of chamber of origin. The magnitude of LVEF improvement correlated with the decline in residual VPD burden (r = 0.475, P = .007). Patients with preexisting LVCM had a more modest but still significant improvement in LV function compared to patients without preexisting LVCM (ΔLVEF 8% vs 13%, P = .046). Multivariate analysis revealed ablation outcome, higher LVEF, and absence of preexisting LVCM were independently associated with LVEF improvement. CONCLUSION Frequent outflow tract VPDs are associated with LVCM regardless of ventricle of origin. Significant (>80%) reduction in VPD burden has comparable improvement in LV function to complete VPD elimination. Successful VPD ablation may be beneficial even in patients with preexisting LVCM.

Electrocardiographic and electrophysiologic features of ventricular arrhythmias originating from the right/left coronary cusp commissure

BACKGROUND Ventricular arrhythmias are known to originate from the aortic sinus of Valsalva. OBJECTIVE The purpose of this study was to identify the characteristics associated with ventricular arrhythmias originating from the right coronary cusp-left coronary cusp (RCC-LCC) commissure. METHODS Thirty-seven consecutive patients with ventricular arrhythmias originating from the aortic cusp region were studied. Intracardiac echocardiography and electroanatomic mapping were used to define coronary cusp anatomy and catheter position. Ventricular arrhythmias from the RCC-LCC commissure were compared with ventricular arrhythmias originating from other sites in the aortic cusp region. RESULTS Nineteen (51%) ventricular arrhythmias had an anatomic origin at the RCC-LCC commissure. Eighteen ventricular arrhythmias originated from other aortic cusp sites (4 right cusp, 7 left cusp, 3 left ventricular endocardium, 4 left ventricular epicardium anterior to aortic valve). A QS morphology in lead V(1) with notching on the downward deflection was present in 15 of 19 ventricular arrhythmias originating from the RCC-LCC commissure compared to 2 of 18 ventricular arrhythmias from other aortic cusp sites (P <.01). At the site of earliest activation, 13 of 19 patients with RCC-LCC ventricular arrhythmias had late potentials in sinus rhythm compared to 1 of 18 ventricular arrhythmias from other aortic cusp sites (P <.01). The site of successful ablation was confirmed to be above the aortic valve plane in 15 (79%) of 19 patients with RCC-LCC ventricular arrhythmias. CONCLUSION RCC-LCC aortic cusp ventricular arrhythmias are common and have a QS morphology in lead V(1) with notching on the downward deflection with precordial transition at lead V(3). In the majority of cases, the site of successful ablation has late potentials in sinus rhythm.

Characterization of the phrenic nerve course within the epicardial substrate of patients with nonischemic cardiomyopathy and ventricular tachycardia.

BACKGROUND Patients with nonischemic cardiomyopathy and ventricular tachycardia (VT) often have low-voltage areas in the lateral left ventricular (LV) epicardium that serve as the VT substrate. The course of the left phrenic nerve in this region may pose a challenge to successful and safe ablation. OBJECTIVE The purpose of this study was to delineate the left phrenic nerve course in patients with nonischemic cardiomyopathy and suspected epicardial VT and to characterize its relationship with the VT substrate. METHODS In 10 patients with nonischemic cardiomyopathy undergoing epicardial VT mapping and ablation, the course of the phrenic nerve was defined by pacing. The extent of epicardial LV low-voltage areas (<1.0 mV) was characterized by electroanatomic voltage mapping. RESULTS Eight of 10 patients had low-voltage areas involving the lateral epicardial LV, and 7 of these 8 patients had sites of phrenic capture within these areas. Ablation was limited due to location of the phrenic nerve in two patients. In one of these patients, a balloon catheter was successfully used to mechanically protect the phrenic nerve during ablation. In the other five patients, adjacent ablation sites were targeted at which no phrenic capture with high-output pacing was demonstrated prior to ablation. In all patients undergoing ablation, the targeted VT became noninducible, and no patient demonstrated phrenic nerve injury. CONCLUSION In most patients with nonischemic cardiomyopathy undergoing epicardial VT ablation, the phrenic nerve courses through a lateral LV low-voltage area in proximity to potential sites for ablation. Strategies to identify and protect the phrenic nerve are important.

Complex fractionated electrogram distribution and temporal stability in patients undergoing atrial fibrillation ablation.

Background: Targeting of complex fractionated electrograms (CFEs) has been described as an approach for catheter ablation of atrial fibrillation (AF); however, the distribution and temporal stability of CFE regions remain poorly defined.

Ablation of ventricular arrhythmias arising near the anterior epicardial veins from the left sinus of Valsalva region: ECG features, anatomic distance, and outcome.

BACKGROUND Left ventricular outflow tract tachycardia/premature depolarizations (VT/VPDs) arising near the anterior epicardial veins may be difficult to eliminate through the coronary venous system. OBJECTIVE To describe the characteristics of an alternative successful ablation strategy targeting the left sinus of Valsalva (LSV) and/or the adjacent left ventricular (LV) endocardium. METHODS Of 276 patients undergoing mapping/ablation for outflow tract VT/VPDs, 16 consecutive patients (8 men; mean age 52 ± 17 years) had an ablation attempt from the LSV and/or the adjacent LV endocardium for VT/VPDs mapped marginally closer to the distal great cardiac vein (GCV) or anterior interventricular vein (AIV). RESULTS Successful ablation was achieved in 9 of the 16 patients (56%) targeting the LSV (5 patients), adjacent LV endocardium (2 patients), or both (2 patients). The R-wave amplitude ratio in lead III/II and the Q-wave amplitude ratio in aVL/aVR were smaller in the successful group (1.05 ± 0.13 vs 1.34 ± 0.37 and 1.24 ± 0.42 vs 2.15 ± 1.05, respectively; P = .043 for both). The anatomical distance from the earliest GCV/AIV site to the closest point in the LSV region was shorter for the successful group (11.0 ± 6.5 mm vs 20.4 ± 12.1 mm; P = .048). A Q-wave ratio of <1.45 in aVL/aVR and an anatomical distance of <13.5 mm had sensitivity and specificity of 89%, 75% and 78%, 64%, respectively, for the identification of successful ablation. CONCLUSIONS VT/VPDs originating near the GCV/AIV can be ablated from the LSV/adjacent LV endocardium. A Q-wave ratio of <1.45 in aVL/aVR and a close anatomical distance of <13.5 mm help identify appropriate candidates.

Efficacy and Risk of Atrial Fibrillation Ablation Before 45 Years of Age

Background—Young patients with atrial fibrillation (AF) tend to be more symptomatic and less willing to take long-term medications, yet catheter ablation remains recommended as second-line therapy for AF regardless of age. This study seeks to characterize the effectiveness and risk of AF ablation in the young. Methods and Results—Consecutive (n=1548) patients who underwent 2038 AF ablation procedures were included. Major procedural complications and efficacy were analyzed on the basis of age at the initial procedure: <45 years (group 1), 45 to 54 years (group 2), 55 to 64 years (group 3), and ≥65 years (group 4). AF control was defined as no or rare AF on or off antiarrhythmic drugs. The primary outcome of AF control was similar in all groups; it was achieved in 87% in group 1, 88% in group 2, 88% in group 3, and 82% in group 4 (P=0.06). However, more group 1 patients demonstrated freedom from AF off antiarrhythmic drugs (76%) compared with group 2 at 68%, group 3 at 65%, and group 4 at 53% (P<0.001). There were no major complications in group 1, 10 (1.7%) in group 2, 14 (1.4%) in group 3, and 10 (2.6%) in group 4 (P=0.01). Conclusions—In patients younger than 45 years, there is a lower major complication rate and a comparable efficacy rate, with a greater chance of being AF free without antiarrhythmic drugs. These findings suggest that it may be appropriate to consider ablative therapy as first-line therapy in this age group.