AF After Cardiac Surgery More Likely in Men, More Deadly in Women

Among patients undergoing cardiac surgery, women are less likely than men to develop postoperative atrial fibrillation (AF) after adjustment for other relevant factors, but long-term mortality is higher for those women who do, according to a new analysis.

The findings suggest the need for not only different risk scores for men and women undergoing cardiac surgery, but also, potentially, sex-based care, according to lead author Sergey Karamnov, MD (Brigham and Women’s Hospital, Boston, MA).

“We treat females and males the same way,” he told TCTMD. “The sizing of the equipment is a little bit different, and the sizing of the valves, . . . but I don't think, anywhere in the country, that any [differentiated] pathways exist to preoperative care, interoperative management, and postoperative management, and long-term follow-up for males and females.”

Also, Karamnov said, “historically, a lot of risk scores that we're using in clinical practice right now are derived from studies that have more males than females in their sample size.”

Commenting for TCTMD, Catherine Wagner, MD (University of Michigan, Ann Arbor), said the study “highlights how there are all of these different disparities throughout postoperative cardiac surgical care and opportunities to risk stratify so that we can get patients to have the best outcomes moving forward.”

Wagner led a recent study that identified a lower rate of guideline-recommended concomitant procedures to treat existing AF among women compared with men undergoing nonmitral cardiac surgeries.

“Gender differences and women's health is kind of [having] a moment within research, which is really exciting to see,” she said. However, because the study looked at long-term morality, which could have several complicating biological and social factors, the findings will remain “hypothesis-generating at this point,” she cautioned.

Sex-Based Interaction

For the analysis, published online today in JAMA Network Open, Karamnov and colleagues looked at data from 21,568 patients (mean age 66.5 years; 30.6% women) undergoing cardiac surgery in the Society of Thoracic Surgeons Adult Cardiac Surgery Database between 2002 and 2016. A slightly higher proportion of women compared with men developed postoperative AF (40.8% vs 38.8%), but on multivariable analysis, women had a lower risk than men (OR 0.85; 95% CI 0.79-0.91).

The incidence of postoperative AF increased the risk of death for both men (HR 1.17; 95% CI 1.11-1.25) and women (HR 1.31; 95% CI 1.21-1.42), but more so for the latter group, resulting in a significant interaction between postoperative AF and sex (HR 1.11 for women vs men; 95% CI 1.02-1.23). There was no such gap in mortality risk among men and women who did not develop postoperative AF.

Karamnov argued that the data provide more confirmatory evidence that postoperative AF is not a benign condition, as previously thought. “Postoperative atrial fibrillation is an ominous complication that leads to increased risk of stroke, increased risk of long-term atrial fibrillation, increased need for anticoagulation and subsequent complications of that,” he said. Given this, when patients develop postoperative AF, especially if they are female, “the follow-up should be more careful [and] home devices have to be utilized more frequently.”

The findings also support further sex-based research into outcomes after cardiac surgery, he said. “[We need] to investigate female patients separately compared to males and not to mix them all up, because I think it actually makes the picture a little bit more murky.”

If risk factors can be identified as key to the disparate mortality in males and females, Karamnov continued, “then we can probably address that on a different level by identifying those females who are at high risk and starting prophylaxis earlier to ensure this complication does not happen.”

Wagner agreed. “As more and more of these gender differences are uncovered, I think people are really understanding that we just need more research in women overall,” she said. “I hope this paper can serve as another call to action for the importance of research stratified by biological sex for outcomes.”

But the findings also have implications for male patients, who are at an increased risk for mortality if they develop postoperative AF, she pointed out.

“One potential driver of the higher mortality for patients with postop A-fib is strokes,” Wagner said, noting that both left atrial appendage ligation and the maze procedure have proven beneficial for stroke prevention in patients with AF. As such, the study “continues to bring awareness of the importance of intervention on A-fib if it's identified preoperatively. But really, this is just the beginning for us to understand how we can truly optimize patient care after cardiac surgery.”