INTRODUCTION

Percutaneous epicardial mapping and ablation play a fundamental role in ventricular tachycardia (VT) ablation, particularly in the context of underlying nonischemic cardiomyopathy where anatomical changes extend to the epicardium or are primarily epicardial in nature.^1–4 Studies have shown that combined endocardial-epicardial VT ablation is associated with a lower VT recurrence rate and mortality compared to endocardial VT ablation alone.^5,6 However, these patients are commonly anticoagulated with either warfarin or direct oral anticoagulants due to the presence of atrial fibrillation (AF).^7–9 It is also common for patients to have left heart endocardial mapping before the need for epicardial access is demonstrated. These patients therefore will already require intravenous heparin administration, which results in having to either perform percutaneous epicardial access with the patient anticoagulated or to undertake preemptive epicardial puncture and mapping prior to endocardial mapping, resulting in unnecessary puncture. Unfortunately, electrocardiogram criteria for identifying an epicardial VT source lacks the sensitivity and specificity to accurately predict which patients might need epicardial ablation.^10–12 An alternative option to avoid epicardial access on heparin is to perform the endocardial and epicardial procedure separately; however, this approach will not only put the patient at increased risk but is also associated with increased healthcare cost. Percutaneous epicardial access has been reported to be reasonably safe, but there are recognized complications associated with this procedure. Sacher et al.¹³ reported in a multicenter safety study that epicardial access was associated with a risk of 5% for acute and 2% for delayed major complications.

One major complication associated with epicardial access is pericardial bleeding, which has been reported at rates around 4% to 13% from data obtained from multicenter and single-center studies.^14–18 The risk of myocardial puncture and bleeding associated with epicardial access has always caused concern about the use of anticoagulation in the context of epicardial access. This is reflected in the 2009 European Heart Rhythm Association (EHRA) and Heart Rhythm Society (HRS) expert consensus,¹⁹ which recommends that epicardial access be obtained prior to the use of systemic anticoagulation or following reversal of anticoagulation therapy. The EHRA position document endorsed by the European Society of Cardiology (ESC), HRS, and Asia Pacific Heart Rhythm Society (APHRS)²⁰ also recommends that oral anticoagulation with a vitamin K antagonist should be withdrawn to achieve an INR of < 1.5, and direct oral anticoagulants should be discontinued for at least 48 hours prior to the procedure. However, since these recommendations were made, several studies have shown that epicardial access on anticoagulation therapy is safe and, in nonrandomized settings, is not associated with a significant increase in complication rates when compared to the complication rates seen in patients not given anticoagulation therapy.^10,21 Further to this, it has been shown that in those patients who have had complications while on anticoagulation therapy, it has not resulted in significant prolongation in hospital stay or mortality.^10,21 This consideration will be explored further in this chapter. A summary of the studies evaluating the safety of epicardial access on anticoagulation therapy is shown in Table 8.1.

Several observational studies have demonstrated that epicardial access in heparinized patients is a safe approach.10,21,22 One of these studies was a single-center study that included 17 patients who underwent epicardial access for VT ablation following intravenous heparin administration with an activated clotting time of > 300 seconds.¹⁰ This study found no major bleeding in any of these patients. In three of the patients in this study, inadvertent puncture of the right ventricle occurred, which did not cause any adverse consequences. Even though the cohort size was small, patients with previous cardiac surgery or pericardial access in whom epicardial access can be difficult did not experience higher rates of complication with heparin administration.

Nakamura and colleagues¹⁸ went on to further assess the impact of heparin administration on epicardial access in a single-center study. A total of 355 patients were included, and these were classified into three separate groups. Group 1 consisted of patients in whom heparin was not administered before epicardial access (n = 260). Group 2 consisted of patients who had heparin administered but reversed prior to the epicardial access (n = 64). Group 3 included patients who had heparin administered without reversal prior to the epicardial access (n = 31). Of the 355 patients, 46 patients (13%) experienced significant pericardial bleeding (> 80 mL); however, there was no significant difference among the three groups (P = 0.72). There also was no significant difference for bleeding in group 3, the patients in whom heparin administration was not reversed, which had the lowest percentage of patients with pericardial bleeding. As one might expect, even though heparinization was not a risk factor, unintentional cardiac puncture was independently associated with the occurrence of pericardial bleeding (OR 16.4; 95% CI 7.35–36.4; P < 0.001). Just as shown in the previous study, in the 38 patients who had inadvertent cardiac puncture, there was no difference in the pericardial bleeding rates between the three groups.

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