Dr. Doug Zipes on Atrial Fibrillation: Updates From ACC 2023

Dr. Zipes: Despite many cardiovascular advances over the past decades, atrial fibrillation remains an albatross vexing both patients and clinicians. And the incidence of this most common type of rapid heartbeat continues to increase in part due to the aging population, as well as increased survival from other cardiological problems such as heart failure that march together with atrial fib.

Now, for years, we've considered atrial fib as a sort of trivial heart rhythm disturbance, easily managed and without major consequences. We've come to realize, however, that we've really underestimated its impact and that it's associated with significant morbidity such as heart failure, strokes, as well as an increase in mortality. And recognizing these effects highlights the need to diagnose atrial fib's presence, particularly since as many as one-third of the episodes may be asymptomatic. We've also learned that lifestyle management including, and very importantly, alcohol cessation, weight reduction, and exercise can help reduce its presence, leading to a decrease in its related comorbidities.

Ablation

Now, ablation of atrial fibrillation has gained widespread acceptance as an initial treatment for many patients, producing better cardiovascular outcomes and quality of life than antiarrhythmic drugs, for example, or rate control. Catheter ablation of arrhythmias can be associated with severe complications, often dependent on the kind of atrial fib, its complexity, whether the pulmonary veins are isolated alone, or there’s more ablation, and patient comorbidities. Importantly, as I’ll come back to, is the experience of the performing centers.

Cryoablation

Now, multiple new publications have advanced the field and particularly highlighted during this year's ACC meeting in New Orleans. While radiofrequency catheter ablation has been the standard, cryoablation, freezing that is, has also been successful. For example, a study published in New England Journal of Medicine by Andrade et al called Progression of Atrial Fibrillation after Cryoablation or Drug Therapy showed that initial treatment of paroxysmal atrial fib with catheter cryoablation was associated with a lower incidence of persistent atrial fib or recurrent atrial tachyarrhythmias over a 3-year follow-up compared to the use of antiarrhythmic drugs.

Pulsed field ablation

Highlighted at this meeting is the newest of ablation techniques. For example, a study by Verma et al published in Circulation called Pulsed Field Ablation for Treatment of Atrial Fibrillation showed that this new ablation technique, that is, pulsed field, was successful in a subset of patients with both paroxysmal and persistent atrial fib, that it was safe and effective and took much less time than radiofrequency catheter ablation.

Now, pulsed field ablation uses electrical pulses to cause nonthermal irreversible electroporation, that is, holes in the cells that induce cardiac cell death. It's been very effective, and it may be the new ablation approach for atrial fib.

Real-world outcomes of ablation

Now, many sites are using atrial fibrillation, and one of the other studies presented is called the Initial Findings From the National Cardiovascular Data Registry of Atrial Fibrillation Ablation Procedures by Hsu et al. And this was to document real-world outcomes of atrial fibrillation. The authors found that early mortality rates were 0.2% in outpatient ablation procedures and higher, 2.4%, for inpatient procedures, and that's most likely explained by the increased comorbidities of patients being admitted to the hospital for the procedure. Pulmonary vein isolation was accomplished in 92% of patients.

High-volume advantage

Now, what struck me as so important in this study was that hospitals with a high overall ablation volume had almost one-third lower odds of early mortality, an odds ratio of 0.69, compared with those with the lowest volume. While all of these numbers are satisfying and low, the critical finding I think is consistent; that is, the high-volume outcome is consistent with multiple other studies on atrial fib and other complicated procedures, including surgery. Expert teams with higher volumes generally experience lower rates of complications and deaths, and that raises the question of whether we should have specialty hospitals in the United States, areas that have high volume for complicated procedures such as atrial fib ablation, and that these complex procedures should not be performed by everyone who is an MD. Obviously, that will raise all kinds of issues, but nevertheless, I think it is an important consideration and one that really much of Europe embraces.

Left atrial appendage occlusion

Now, it's interestingly important that techniques other than ablation can be used to reduce the risk of stroke in patients with atrial fib. Another study presented at the ACC by Kogan et al and published in Stroke is called Early Stroke and Mortality After Percutaneous Left Atrial Appendage Occlusion in Patients With Atrial Fibrillation. This was a retrospective registry analysis of patients between 2016 and ‘19 and sought to document the incidence of early 90-day stroke and mortality after left atrial appendage occlusion, and it included over 42,000 left atrial appendage occlusion procedures, and it showed a low incidence of stroke, only 0.63%, and mortality, 0.53%, as well as a low incidence of procedural complications, 2.59%.

I think those are pretty remarkable outcomes. Other studies have shown that this left atrial appendage occlusion approach is noninferior compared with anticoagulation. So, the take-home message is that this particular procedure remains safe despite its rapid and wide dissemination, the procedure being used by many physicians around the world. Long-term issues with the left atrial appendage occlusion are peridevice leak and possible thrombosis in the device.

Advances, but more to be done

So, we can see that there have been many advances in treating and diagnosing our patients with atrial fib. Many issues remain such as screening and diagnosis, for example, using wearable technologies in the future, but it's very gratifying to see that these advances are occurring and will improve the lives of our atrial fibrillation patients.