About 15 to 20 percent of Americans will suffer from atrial fibrillation—a chaotic electrical pattern in the upper chambers of the heart—during their lifetimes. It can cause substantial symptoms including shortness of breath and heart palpitations, and it increases the risk for stroke. Catheter ablation, in which cardiologists use radiofrequency energy burning or freezing technology to inhibit the electrical signals triggering the condition in the pulmonary veins, is an effective procedure for decreasing atrial fibrillation burden and improving a patient’s quality of life. But a new Yale study has found that not only do women patients experience a poorer quality of life than men by the time they are referred for ablation, but they also are at increased risk for adverse outcomes after the procedure.
The research, led by James Freeman, MD, MPH, associate professor of medicine (cardiology), followed a contemporary cohort of 58,960 patients and is the first registry-based study of its size analyzing sex-based differences in the procedural complications around atrial fibrillation ablation. The team published its findings in Heart on September 14.
“This study is a call to arms to continue efforts to mitigate the risk of these procedures and continue to try to improve the safety profile for women,” says Freeman.
Risks for Women Persist Despite Advances
Over the past decade, cardiologists have made strides in improving the safety of catheter ablation and shown a greater understanding of the anatomical differences in women. They tend to be smaller than men, for example. Many medical centers around the country now use ultrasound for more accurate vascular access and placement of the catheters used for ablation instead of just feeling for a pulse. Current generation catheters allow cardiologists to know how much force is being delivered while performing the ablation and help them reduce the risk of perforation in women’s smaller hearts. And there is increased awareness around the sex-based differences in the appropriate dosing of blood thinners peri-procedurally.
While these efforts have led to a decline in post-procedure complications, Freeman’s team wanted to better understand whether sex-based differences persist. The American College of Cardiology has created a series of databases known as the National Cardiovascular Data Registry (NCDR). The researchers obtained data from the NCDR’s AFib Ablation Registry to evaluate nearly 60,000 patients across 150 U.S. sites seen between January 2016 and September 2020.
First, the team divided the patients by sex and studied their baseline characteristics, including age and any comorbidities. Next, they looked at differences in overall adverse events rates, major adverse events rates, and hospitalizations longer than a day.
The study revealed several major differences. Men, for instance, tended to experience persistent atrial fibrillation. Women, on the other hand, were mostly paroxysmal, meaning they went in and out of atrial fibrillation and were often more symptomatic. For instance, they frequently had heart palpitations, chest pain, fatigue, and dizziness. Women also tended to be older than men by the time they underwent ablation and were experiencing a significantly lower quality of life before undergoing the procedure.
“This suggests that there may be an opportunity for cardiologists to treat women earlier in the course of their disease than we are,” says Freeman.
This study is a call to arms to continue efforts to mitigate the risk of these procedures and continue to try to improve the safety profile for women.
James Freeman, MD, MPH
Even after controlling for older age and comorbidities, the researchers found that women were more likely to experience a range of complications after undergoing catheter ablation. They were at greater risk of pericardial effusion, which can occur when a surgeon inadvertently perforates the heart and leads to a buildup of blood in the pericardial space around the heart that can be life-threatening. Women also showed higher rates of bradycardia [slow heart rates] requiring a permanent pacemaker. They were more likely to experience injury of the phrenic nerve, which runs directly adjacent to the left atrium and innervates the diaphragm. Phrenic nerve injury can paralyze the diaphragm, causing difficulties with breathing.
Women were more likely to have vascular injury and bleeding in the adjacent groin area that requires surgical intervention. They also had higher rates of volume overload, in which fluid buildup occurs in the lungs and can cause shortness of breath or heart failure. Treating volume overload requires medication to get rid of the fluid and prolong hospitalization. “One of the greatest advantages of our study compared with prior studies is that we were able to look at a lot of specific adverse events that had not been previously well-studied,” Freeman says.
Women were more likely to be hospitalized for longer periods of time. “There is a real opportunity to minimize health resource utilization,” says Freeman. “If a significant number of women are having to stay in the hospital for an extra day, that’s not insubstantial.”
A Call to Improve Health and Safety for Women
Despite recent advances, there still is work to do to improve the quality of lives of women with atrial fibrillation and also their safety when undergoing catheter ablation. Freeman’s research offers clarity on the specific complications women face that drive adverse event rates, and he hopes it will provide direction as cardiologists work to continue to make the procedure safer for their women patients. He hopes to continue studying sex-based differences in the future to monitor how trends have progressed over time.
“Despite awareness around the complications of ablation, we’re still seeing persistent complications,” says Freeman. “Time and time again, these procedures are improving patients’ quality of life and symptom burden. But we must continue our efforts to mitigate the risk.”