Intra-procedural anticoagulation protocols for left-sided cardiac ablations: Striking a balance between risk and benefit

Left-sided cardiac ablations comprise a large portion of all catheter ablation procedures performed worldwide, with atrial fibrillation (AF) ablation amounting to the largest share of the procedural volume. The effectiveness of catheter ablation varies depending on the targeted arrhythmia itself, the cardiac substrate, the patient's comorbidities and the operator's experience. Achieving sustained ablation results and patient outcomes for certain arrhythmias remains a challenge, particularly for AF and ventricular tachycardia (VT) in structural heart disease [1,2], thus the clinical value of these procedures is largely determined also by their safety. The safety of ablation procedures has improved in the last several years through a better understanding of the procedural risks and advancements in technique and technology [3]. However, thrombus formation and embolism during and shortly after the procedure remains a major concern with catheter ablation of the left-sided cardiac chambers. This can be manifested as symptomatic or asymptomatic cerebral embolism [4]. In a large inpatient sample in the United States undergoing catheter ablation for AF, the overall incidence of stroke or transient ischemic attack was 1.02% [5]. Data is generally sparser regarding the risk of thromboembolism with left ventricular ablations. In a recent multicenter analysis of 2061 patients undergoing ablation of infarct-related VT, the rate of stroke or transient ischemic attack was 0.5% in the periprocedural period [6]. Such events in left-sided ablations may be due to catheter manipulation of pre-formed intracardiac thrombus, de novo coagulum formation on the catheters and at the sites of endocardial tissue damage with ablation, aortic atheromatous plaque material that can be embolized with catheter contact in retrograde approaches, or due to bubbles of air collected in the long sheaths during catheter exchange. It is also notable that many patients undergoing cardiac ablations have a substrate that may further predispose to thombogenesis as they tend to be older, have enlarged cardiac chambers and may have low-grade inflammatory or prothrombotic states. In this setting, the importance of meticulous anticoagulation has been well recognized and is a fundamental component of left-sided ablation procedures.