Withholding NOACs prior to ablation for AF may yield brain lesions
Withholding new oral anticoagulants (NOACs) prior to performing left atrial radiofrequency ablation in patients with atrial fibrillation (AF) is associated with an increased risk of asymptomatic cerebral lesions, a prospective study has shown. This raises the question of whether brain lesions on MRI could lead to cognitive decline over time.
The rate of brain lesions in patients who had previously been prescribed a NOAC but went off the drug a day before ablation (standard practice at that time) was higher at 17.3 percent (p=0.049). By comparison, those who stayed on a prescribed vitamin K antagonist (VKA) therapy throughout the procedure had a 9.6 percent rate of asymptomatic, mostly small, cerebral lesions on MRI post ablation. [EHRA EUROSPACE-CARDIOSTIM 2017, abstract P247]
“The study does not imply that VKAs should be preferred over NOACs prior to AF ablation,” said lead author Dr Michael Derndorfer from the Elisabethinen University Teaching Hospital in Linz, Austria said. Rather, it underscores the importance of uninterrupted anticoagulation throughout ablation. “It was the discontinuation why we had an astonishingly high rate of asymptomatic cerebral lesions in the NOAC group.”
The study included 410 patients who had a routine cerebral MRI pre and post standard pulmonary vein isolation (PVI) for AF. Patients were on a background NOAC (rivaroxaban, dabigatran, or apixaban) or coumarin derivatives (phenprocoumon or acenocoumarol). About two-thirds had paroxysmal AF and one-third had persistent AF. Less than a third were women. The duration of AF and history of hypertension, stroke, transient ischaemic attack, and diabetes was comparable between groups.
It was standard practice previously to stop NOACs prior to ablation due to an increased risk of bleeding. However, greater experience with NOACs shifts the practice to keeping patients on anticoagulants or VKAs during the procedure even if heparin is introduced to prevent a stroke.
In the current study, larger left atrial diameter, higher stroke risk scores, and a lower achieved activated clotting time (ACT) at the time of the procedure were among the predictors of cerebral lesions. Derndorfer cannot say what the long-term effects of cerebral lesions are, but some studies suggest that they could lead to cognitive decline in the future.
Although procedural heparin was titrated to an ACT of 300 to 400 seconds according to current recommendations, the mean achieved ACT was significantly lower in those whom the NOACs were withdrawn. Left atrial procedure time in minutes was comparable between groups (179. 5 vs 171.9 for NOACs and VKA, respectively) so was distribution of PVI procedures. All-cause mortality, stroke, and need for cardiac surgery intervention did not occur in both groups.
Experts said the study is unreproducible as performing pre and postprocedural MRI to check for cerebral lesions in every patient is both complex and costly. This puts a premium on weighing the available evidence concerning the risks and benefits of withholding NOACs prior to ablation.