Author + information
- Sandeep Prabhu, MBBS and
- Peter M. Kistler, MBBS, PhD∗ ()
- ↵∗Clinical Electrophysiology Research, The Baker Heart & Diabetes Institute, 75 Commercial Road, Melbourne, Victoria, 3004 Australia
The CAMERA-MRI (Catheter Ablation Versus Medical Rate Control in Atrial Fibrillation and Systolic Dysfunction) study was designed to highlight the role of atrial fibrillation (AF) in unexplained heart failure and the notion that restoration of sinus rhythm with catheter ablation would result in significant improvement in left ventricular systolic dysfunction (1). Pulmonary vein isolation (PVI) followed by posterior wall isolation was the preferred ablation strategy in patients randomized to catheter ablation as part of the CAMERA-MRI trial. Posterior wall isolation can be challenging likely due to variations in the extent and thickness of the septopulmonary bundle descending into the posterior left atrium. We have had extensive experience with posterior wall isolation and have published an acute success of 91% in 161 patients with persistent AF with long-term freedom from AF in 85% (2). We agree with Hsu and colleagues that this ablation approach may not be generalizable to less experienced, smaller volume operators. Whether an ablation strategy confined to PVI alone in patients with persistent AF and heart failure would be associated with an equivalent success is unclear. Posterior wall isolation was not part of the adjunctive strategies in the STAR2 AF (Substrate and Trigger Ablation for Reduction of Atrial Fibrillation Trial Part II) multicenter randomized study (3). The role of posterior wall isolation in addition to PVI in persistent AF ablation is the subject of randomized studies including the CAPLA (Catheter Ablation of the Posterior Left Atrium) study (ACTRN12616001436460). A small proportion (6%) of patients did not undergo posterior wall isolation at the operator discretion due to procedure length, patient stability, and concerns regarding esophageal injury.
At the time of this study, esophageal temperature monitoring was not in routine use at the centers involved in this study. Routine measures to minimize esophageal injury included visualization of the esophagus with cardiac computed tomography and intraprocedural transesophageal echocardiography limiting the duration and power of catheter ablation on the posterior wall to 25 W, avoiding excessing (>40 g) contact force and short-term proton pump inhibitor therapy were used for all patients. There were no esophageal complications in the CAMERA-MRI study. Esophageal temperature monitoring is now routinely used following the release of the 2017 expert consensus statement on catheter ablation of AF (4).
Importantly, the primary aim of the CAMERA-MRI study (1) was to evaluate the impact of sustained sinus rhythm upon ventricular function (achieved through catheter ablation) in those patients with rate-controlled persistent AF and an otherwise unexplained cardiomyopathy and in whom pharmacological rhythm control had failed. It was neither powered nor designed to evaluate the impact of a specific ablation strategy upon long-term outcomes. We await with interest the longer-term outcomes of catheter ablation in this population and randomized studies to identify the optimal ablation strategy in patients with persistent AF, and concurrent left ventricular dysfunction.
Please note: This was an investigator-initiated study. St. Jude Medical (Roseville, Minnesota) provided 14% of ILRs used in this study ex gratia. However, St. Jude Medical provided no funding and had no role in study design, data collection, data analysis, data interpretation, or writing of the report. There were no other industry funding sources. Dr. Prabhu has received funding from Australian National Health and Medical Research Council (NHMRC) and/or the National Heart Foundation of Australia, as well as funding from the Baker Heart and Diabetes Research Institute (Melbourne, Australia). Dr. Kistler has received funding from St. Jude Medical for consultancy and speaking engagements; and was in part supported by the NHMRC. This research is supported in part by the Victorian Government’s Operational Infrastructure Funding.
- 2018 American College of Cardiology Foundation
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