Left Ventricular Catheter Ablation May Lead to Cerebral Emboli

By Marilynn Larkin

February 03, 2017

NEW YORK (Reuters Health) - Patients undergoing left ventricular (LV) endocardial ablation are at "significant risk" of developing cerebral emboli, California-based researchers report.

Dr. Gregory Marcus of the University of California, San Francisco, told Reuters Health, "Catheter ablation can be a very effective and safe solution to potentially eradicate frequent extra beats arising from the lower chamber of the heart that are either causing bothersome symptoms or contributing to heart failure."

"Previous studies have suggested that some catheter-based procedures involving the left atrium might result in evidence of asymptomatic and very small injury to the brain in a minority of cases," he said by email. "However, these findings had been attributed to factors not previously thought to be relevant in generally healthy patients undergoing catheter ablation of premature ventricular contractions (PVCs) or ventricular tachycardia."

"We not only found evidence of new brain lesions after these procedures, but in fact found them in the majority of patients," he noted. "Due to the expense of the MRIs required for such an investigation (which at least up until now were not considered standard of care in these patients) and the cost of simply scheduling the MRIs before and precisely after the procedure, such a study has not been previously performed."

As reported in Circulation, online January 24, Dr. Marcus and colleagues enrolled 18 patients scheduled for ablation of ventricular tachycardia (VT) or PVC. The mean age was 58; half were men, half had a history of hypertension and the majority had no known vascular disease or heart failure.

Twelve underwent LV ablation (two for VT and 10 for PVC), and results were compared with six control patients who underwent right ventricular (RV) ablation (one for VT and five for PVC). A brain MRI was performed on each patient before and within a week after the procedure.

Seven patients (58%) had a total of 16 cerebral emboli after LV ablation, compared with none after RV ablation (p=0.04). Seven of 11 patients (63%) managed with a retrograde approach to the left ventricle developed at least one new brain lesion.

Dr. Marcus explained, "Given no evidence of new brain injury with right-sided procedures, we suspect the high rate of new brain injury in these patients may be related to the approach we generally take - specifically, the standard practice is to introduce our ablation catheter via the femoral artery, up the aorta, around the aortic arch and across the aortic valve. While only based on speculation at this point, it's possible we are inadvertently dislodging debris from the blood vessel wall or heart valve as the ablation catheter traverses this path, which then travels to the brain."

"There are other potential explanations," he continued, "such as the formation of blood clots during the procedure, which then dislodge and travel to the brain. However, the risk of blood clot formation is well known and likely mitigated by the blood thinning agents that are routinely administered during these procedures."

"While these patients described no new symptoms and exhibited no abnormalities on physical examination, some evidence from other studies suggest that these small lesions in the brain might be associated with more subtle cognitive decline," he noted. "On the other hand, previous studies have shown that these small lesions can resolve if repeat MRIs are performed a few weeks later.

Dr. Marcus emphasized that catheter ablation of PVC and VT is still "very useful and generally remarkably safe." Nevertheless, he concluded, "These new data point to another risk that we as physicians must weigh when we counsel our patients and consider the best options for them. Most importantly, we and others will be continuing our research to identify the precise mechanism underlying these findings and optimal ways to avoid these new lesions."

Dr. Shephal Doshi, director of cardiac electrophysiology at Providence Saint John's Health Center in Santa Monica, California, told Reuters Health, "Recent studies have increased awareness of potential frequency of brain emboli after atrial fibrillation ablation. While our focus has primarily been in this arena, many experts in the field of catheter ablation have been concerned about the potential risk of embolic events in the group undergoing left ventricular ablation."

The implications of the current study are "substantial," Dr. Doshi observed. "While this study involved only 18 patients, the numbers of embolic events in the small group are fairly striking. This occurred despite using current catheter technology and appropriate levels of anticoagulation. It is also important to recognize that patients with documented evidence of brain emboli most often (did not have) symptoms of clinically apparent stroke."

"Based on this data, there is a clear need for further study to develop strategies to prevent cerebral emboli with catheter ablation, especially left ventricular endocardial ablation," Dr. Doshi said.

Whether transseptal access of the left ventricle may be associated with lower cerebral emboli risk "needs to be validated in larger studies," he said. "The long-term sequelae of these asymptomatic brain emboli also need further research."

SOURCE: https://bit.ly/2kmDmlr

Circulation 2017.