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A history of atrial fibrillation (Afib) was a "harbinger" of death after percutaneous coronary intervention (PCI), researchers suggested.

, of the University of Michigan Cardiovascular Center in Ann Arbor, and colleagues that Afib was independently associated with higher risks of:

• Post-procedural bleeding (OR 1.32, 95% CI 1.15-1.52)
• Heart failure (OR 1.33, 95% CI 1.17-1.52)
• Cardiogenic shock (OR 1.26, 95% CI 1.08-1.48), and
• In-hospital mortality (OR 1.41, 95% CI 1.18-1.68)

Bare metal stents were more likely to be the device of choice for Afib patients (27% versus 18%), according to propensity-matched analysis.

"The association of Afib with mortality after PCI was consistent across a spectrum of presentation types. Resources could be targeted to further evaluate the factors responsible for this association and to lower morbidity and mortality in this high-risk subgroup," the authors wrote.

"The data presented herein are consistent with the theory that Afib represents underlying cardiomyopathy, as a history of Afib was found to be an independent risk factor for poor clinical outcomes related to hemodynamic alterations and pump function," they suggested.

The proportion of patients with Afib varied widely across hospitals (ranging from 2.5% to 18.4%), leading Gurm's group to suggest that Afib be considered in risk models used to rate hospitals and operators.

"It is possible that this variation is a true reflection of differences in case mix, but it is also possible that participating sites varied in terms of the intensity of their documentation or abstraction processes," countered , and , both of Yale University School of Medicine in New Haven, Conn.

Curtis and Akar asked in : "How does a history of (potentially remote) Afib contribute to the increased risk of short-term outcomes of PCI patients?" They went on to question the conventional wisdom that Afib and stroke are causally linked.

"Afib patients did not have a higher incidence of stroke, which would have been expected on the basis of the long-standing theory of Afib-associated hypercoagulability," they noted. "The concept of Afib as a direct cause of stroke and adverse outcomes has been a long-standing tenet in the practice of medicine, but this may warrant reexamination.

"If Afib was a direct cause of thrombogenesis, then why are 'lone Afib' patients (CHADS2-VASC score=0) at such low risk of stroke that current guidelines do not recommend anticoagulation, despite these patients being in persistent Afib? How can one reconcile the findings of several large randomized trials in which Afib burden was accurately measured using implanted devices, demonstrating no temporal correlation whatsoever between Afib episodes and stroke events?"

Gurm's observational study included 13,912 patients with a history of Afib out of a total of 113,283 participants in the Blue Cross Blue Shield of Michigan Cardiovascular Consortium (12.3%).

Patients with a history of Afib were older and had higher odds of having congestive heart failure, cardiomyopathy, cerebrovascular disease, and chronic lung disease.

Gurm and colleagues pointed out that their data came from just one state. Additionally, "the data is drawn from hospitals participating in a quality-improvement initiative, and it is unclear if the findings would apply to hospitals not participating in such an initiative."

And, Curtis and Akar argued that the study authors' use of propensity matching may still have allowed unmeasured but important differences between groups to influence the results.

The editorialists called it "remarkable" how shaky the evidence base regarding PCI for patients with Afib remains.

"Think about it: drug-eluting stents were introduced into clinical practice 13 years ago. If we conservatively estimate that 5% of PCI patients have Afib, we have likely implanted drug-eluting stents in patients with Afib at least 250,000 times. A number of randomized trials are in progress, but our best evidence today consists of a randomized trial that enrolled 573 patients.

"We have to do better than this. We need to create a learning health care system where we can rapidly conduct the large, simple, and reasonably priced randomized trials that we desperately need to inform clinical practice," the pair urged.