Atrial fibrillation (AFib), the most common type of heart rhythm disorder, causes several symptoms like fast or erratic heartbeat, shortness of breath, chest pain, and fatigue, and also increases a person's risk of stroke. To manage AFib symptoms and reduce stroke risk, medical and procedural treatments like ablation are commonly employed. Now, a study has found that a new ablation technology known as pulsed field ablation successfully eliminated episodes of abnormal heart rhythms for 12 months in up to two-thirds of patients.

The study by researchers at McGill University Health Centre (Montreal, Canada) was the first prospective, global clinical trial for the use of pulsed field ablation, which issues electrical pulses, for treating AFib. Ablation is a minimally invasive catheter-based procedure that disables portions of heart tissue causing irregular heart rhythms. For decades, thermal ablation has remained the standard ablation method for AFib. However, pulsed field ablation differs from thermal ablation as it uses electricity instead of extreme temperatures to disable cardiac cells. Using this technology, ablation procedures can be carried out in less time and with less risk of damage to surrounding tissues compared to thermal ablation, according to the researchers.

Standard thermal ablation procedures require a physician to thread tiny instruments to the heart through a vein or artery. By utilizing heat (radiofrequency energy) or freezing cold (cryoablation), small scars in specific atrial regions are then created. Nevertheless, thermal ablation techniques pose a risk of damaging nearby tissues and structures such as nerves and the esophagus. In contrast, pulsed field ablation makes use of electrical fields to create tiny holes in the membranes of heart muscle cells. This causes destruction of the targeted cells that contribute to irregular heart rhythms without altering the general tissue structure or affecting other cell kinds. For over a decade, pulsed field ablation has been employed for cancer treatment by killing tumor cells. However, recently, this particular technology has been utilized on the heart.

Conducted at 41 sites in Canada, Australia, Austria, Belgium, France, Japan, the Netherlands, Spain, and the US, the PULSED AF study enrolled individuals who still experienced AFib, despite the use of medication to improve heart rhythm regulation. For the trial, physicians treated a total of 60 patients, each of them experiencing a single treatment to gain experience with the method. The researchers proceeded to enroll additional patients and performed pulsed field ablations up to 300 procedures across all sites. The researchers then examined the final outcomes from these procedures. Half of the group had episodes of paroxysmal AFib, which ends on its own and lasts for no longer than a week while the other half had persistent AFib, which endures for at least a week and does not end independently. The results showed that 66% of patients with paroxysmal AFib and 55% of those with persistent AFib experienced no AFib episodes between three and 12 months after their procedures, which was the primary endpoint of the trial, as measured through weekly and symptomatic self-reports, electrocardiograms, and 24-hour Holter monitoring. The researchers have affirmed that these rates of efficacy are on par with outcomes from thermal ablation procedures.

In addition, all participants recorded significant and meaningful improvements in their quality of life. Both patient cohorts had one single adverse event, resulting in an adverse event rate of 0.7%. The researchers have noted that most pulsed field ablation procedures took less than an hour, making them much speedier than thermal ablation procedures, which typically take two hours or more. However, the lack of a control group limited the trial and there is a need for extensive research with larger groups to gather more definitive evidence of the process's safety as adverse events from cardiac ablation are generally rare. Thus, larger studies could assist in determining the success rate and the safety of pulsed field ablation. The researchers assert that further technological advances could lead to improved success rates and safety for this procedure.

"The efficacy of the procedure is similar to what we see in thermal ablation, but we're getting it much faster and with much more safety. That is a major development for the field of electrophysiology," said Atul Verma, MD, head of cardiology at McGill University Health Centre in Montreal, Canada, and the study's lead author. "There's been a huge amount of enthusiasm over this technology in the electrophysiology community. Many physicians feel that pulsed field ablation will become the dominant way of doing ablation moving forward, so in that sense, it's really a paradigm shift." 

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