Magnetic resonance imaging-confirmed ablative debulking of the left atrial posterior wall and septum for treatment of persistent atrial fibrillation: rationale and initial experience.

INTRODUCTION: Though pulmonary vein (PV) isolation has been widely adopted for treatment of atrial fibrillation (AF), recurrence rates remain unacceptably high with persistent and longstanding AF. As evidence emerges for non-PV substrate changes in the pathogenesis of AF, more extensive ablation strategies need further study. METHODS: We modified our PV antrum isolation procedure to include abatement of posterior and septal wall potentials. We also employed recently described image-processing techniques using delayed-enhancement (DE) MRI to characterize tissue injury patterns 3 months after ablation, to assess whether each PV was encircled with scar, and to assess the impact of these parameters on procedural success. RESULTS: 118 consecutive patients underwent debulking procedure and completed follow-up, of which 86 underwent DE-MRI. The total left atrial (LA) radiofrequency delivery correlated with percent LA scarring by DE-MRI (r = 0.6, P < 0.001). Based on DE patterns, complete encirclement was seen in only 131 of 335 PVs (39.1%). As expected, Cox regression analysis showed a significant relationship between the number of veins encircled by delayed enhancement and clinical success (hazard ratio of 0.62, P = 0.015). Also, progressive quartile increases in postablation posterior and septal wall scarring reduced recurrences rates with a HR of 0.65, P = 0.022 and 0.66, P = 0.026, respectively. CONCLUSION: Pathologic remodeling in the septal and posterior walls of the LA helps form the pathogenic substrate for AF, and these early results suggest that more aggressive treatment of these regions appears to correlate with improved ablation outcomes. Noninvasive imaging to characterize tissue changes after ablation may prove essential to stratifying recurrence risk.

The Decisions, Interventions, and Goals in ImplaNtable Cardioverter-DefIbrillator TherapY (DIGNITY) Pilot Study.

BACKGROUND: Implantable cardioverter-defibrillators (ICDs) are commonly implanted in older patients, including those with multiple comorbidities. There are few prospective studies assessing the clinical course and end-of-life circumstances for these patients. METHODS AND RESULTS: We prospectively followed 51 patients with ICDs for up to 18 months to longitudinally assess in terms of (1) advance care planning, (2) health status, (3) healthcare utilization, and (4) end-of-life circumstances through quarterly phone interviews and electronic medical record review. The mean age was 71.1±8.3, 74.5% were men, and 19.6% were non-white. Congestive heart failure was predominant (82.4%), as was chronic kidney disease (92%). At baseline, a total of 12% of subjects met criteria for major depression, and 78.4% met criteria for mild cognitive impairment. From this initial study cohort, 76% survived to 18 months and completed all follow-up interviews, 18% died, and 19% withdrew or were lost to follow-up. Though living will completion and healthcare proxy assignment were common (cumulative outcome at 18 months 88% and 98%, respectively), discussions of prognosis were uncommon (baseline, 9.8%; by 18 months, 22.7%), as were conversations regarding ICD deactivation (baseline, 15.7%; by 18 months, 25.5%). Five decedents with available data received shocks in the days immediately prior to death, including 3 of whom ultimately had their ICDs deactivated prior to death. CONCLUSIONS: We demonstrated the feasibility of prospective enrollment and follow-up of older, vulnerable ICD patients. Early findings suggest a high burden of cognitive and psychological impairment, poor communication with providers, and frequent shocks at the end of life. These findings will inform the design of a larger cohort study designed to further explore the experiences of living and dying with an ICD in this important patient population.

Evaluation of left atrial lesions after initial and repeat atrial fibrillation ablation: lessons learned from delayed-enhancement MRI in repeat ablation procedures.

BACKGROUND: We evaluated scar lesions after initial and repeat catheter ablation of atrial fibrillation (AF) and correlated these regions to low-voltage tissue on repeat electroanatomic mapping. We also identified gaps in lesion sets that could be targeted and closed during repeat procedures. METHODS AND RESULTS: One hundred forty-four patients underwent AF ablation and received a delayed-enhancement MRI at 3 months after ablation. The number of pulmonary veins (PV) with circumferential lesions were assessed and correlated with procedural outcome. Eighteen patients with AF recurrence underwent repeat ablation. MRI scar regions were compared with electroanatomic maps during the repeat procedure. Regions of incomplete scar around the PVs were then identified and targeted during repeat ablation to ensure complete circumferential lesions. After the initial procedure, complete circumferential scarring of all 4 PV antrum (PVA) was achieved in only 7% of patients, with the majority of patients (69%) having <2 completely scarred PVA. After the first procedure, the number of PVs with complete circumferential scarring and total left atrial wall (LA) scar burden was associated with better clinical outcome. Patients with successful AF termination had higher average total left atrial wall scar of 16.4%+/-9.8 (P=0.004) and percent PVA scar of 66.2+/-25.4 (P=0.01) compared with patients with AF recurrence who had an average total LA wall scar 11.3%+/-8.1 and PVA percent scar 50.0+/-24.7. In patients who underwent repeat ablation, the PVA scar percentage was 56.1%+/-21.4 after the first procedure compared with 77.2%+/-19.5 after the second procedure. The average total LA scar after the first ablation was 11.0%+/-4.1, whereas the average total LA scar after second ablation was 21.2%+/-7.4. All patients had an increased number of completely scarred pulmonary vein antra after the second procedure. MRI scar after the first procedure and low-voltage regions on electroanatomic mapping obtained during repeat ablation demonstrated a positive quantitative correlation of R(2)=0.57. CONCLUSIONS: Complete circumferential PV scarring difficult to achieve but is associated with better clinical outcome. Delayed-enhancement MRI can accurately define scar lesions after AF ablation and can be used to target breaks in lesion sets during repeat ablation.

MRI in cardiac electrophysiology: the emerging role of delayed-enhancement MRI in atrial fibrillation ablation.

Catheter ablation of atrial fibrillation has emerged as a viable therapeutic option for those patients who have failed conventional medical therapy. This treatment strategy has been introduced in the past decade following the discovery of ectopic foci in the pulmonary veins capable of initiating this arrhythmia. The basis of current ablation techniques relies on inducing myocardial necrosis at distinct anatomical landmarks in order to electrically isolate these ectopic foci and to disrupt pulmonary vein and left atrial conduction pathways. The recent introduction of a delayed-enhancement cardiac MRI sequence now allows for the noninvasive assessment of the location and extent of left atrial scarring following the ablation procedure. In this review, we describe this novel scan sequence and its current and potential role in catheter ablation of atrial fibrillation.

Initial experience of assessing esophageal tissue injury and recovery using delayed-enhancement MRI after atrial fibrillation ablation.

BACKGROUND: Esophageal wall thermal injury after atrial fibrillation ablation is a potentially serious complication. However, no noninvasive modality has been used to describe and screen patients to examine whether esophageal wall injury has occurred. We describe a noninvasive method of using delayed-enhancement MRI to detect esophageal wall injury and subsequent recovery after atrial fibrillation ablation. METHODS AND RESULTS: We analyzed the delayed-enhancement MRI scans of 41 patients before ablation and at 24 hours and 3 months after ablation to determine whether there was evidence of contrast enhancement in the esophagus after atrial fibrillation ablation. In patients with contrast enhancement, 3D segmentation of the esophagus was performed using a novel image processing method. Upper gastrointestinal endoscopy was then performed. Repeat delayed-enhancement MRI and upper gastrointestinal endoscopy was performed 1 week later to track changes in lesions. The wall thickness of the anterior and posterior wall of the esophagus was measured at 3 time points: before ablation, 24 hours after ablation, and 3 months after ablation. Evaluation of preablation MRI scans demonstrated no cases of esophageal enhancement. At 24 hours, 5 patients showed contrast enhancement. Three of these patients underwent upper gastrointestinal endoscopy, which demonstrated esophageal lesions. Repeat upper gastrointestinal endoscopy and MRI 1 week later demonstrated resolution of the lesions. All 5 patients had confirmed resolution of enhancement at 3 months. All patients with esophageal tissue enhancement demonstrated left atrial wall enhancement directly adjacent to the regions of anterior wall esophageal enhancement. CONCLUSIONS: Our preliminary results indicate delayed-enhancement MRI can assess the extent and follow progression of esophageal wall injury after catheter ablation of atrial fibrillation. It appears that acute esophageal injury recovers within 1 week of the procedure.

Temporal left atrial lesion formation after ablation of atrial fibrillation.

BACKGROUND: Atrial fibrillation (AF) ablation uses radiofrequency (RF) energy to induce thermal damage to the left atrium (LA) in an attempt to isolate AF circuits. This injury can be seen using delayed enhancement magnetic resonance imaging (DE-MRI). OBJECTIVE: The purpose of this study was to describe DE-MRI findings of the LA in the acute and chronic stages postablation. METHODS: Twenty-five patients were scanned at two time points postablation. The first group (n = 10) underwent DE-MRI at 24 hours and at 3 months. The second group (n = 16) was scanned at 3 months and at 6 or 9 months. One patient had three scans (24 hours, 3 months, 9 months) and was included in both groups. The location and extent of enhancement were then analyzed between both groups. RESULTS: The median change in LA wall injury between 24 hours and 3 months was -6.38% (range -11.7% to 12.58%). The median change in LA wall injury between 3 months and later follow-up was +2.0% (range -4.0% to 6.58%). There appears to be little relationship between the enhancement at 24 hours and 3 months (R(2) = 0.004). In contrast, a strong correlation is seen at 3 months and later follow-up (R(2) = 0.966). Qualitative comparison revealed a stronger qualitative relationship between MRI findings at 3 months and later follow-up than at 24 hours and 3 months. CONCLUSION: RF-induced scar appears to have formed by 3 months postablation. At 24 hours postablation, DE-MRI enhancement appears consistent with a transient inflammatory response rather than stable LA scar formation.