Oral Anticoagulation Underused in Japanese A-fib Patients Undergoing PCI

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Many patients with atrial fibrillation (A-fib) who are treated in Japan receive suboptimal oral anticoagulation after undergoing percutaneous coronary intervention (PCI), reports a registry study published online April 25, 2014, ahead of print in the American Journal of Cardiology.

In the CREDO-Kyoto 2 registry, Satoshi Shizuta, MD, of Kyoto University Graduate School of Medicine (Kyoto, Japan), and colleagues identified 1,057 patients with A-fib who represented 8.3% of the 12,716 patients undergoing first PCI at 26 centers between 2005 and 2007. Median follow-up duration was 5.1 years. Cumulative incidence of stroke at 5 years was higher in the A-fib group (12.8%) than in patients without the condition (5.8%; P < .0001); this excess risk remained after adjustment for confounders.

Three-quarters of A-fib patients had CHADS₂ score ≥ 2. Even so, fewer than half (47.9%) received anticoagulation with warfarin at discharge. The anticoagulation group had higher prevalence of persistent or permanent A-fib but similar CHADS₂ score compared with the non-anticoagulation group.

TTR, Antiplatelet Therapy Affect Stroke Risk

Overall, the 5-year incidence of stroke did not differ by whether patients were or were not given oral anticoagulation (13.8% vs 11.8%; P = .049).

However, within the anticoagulation group, time in therapeutic range (TTR) was only 52.6%, and the international normalized ratio (INR) was 1.6 to 2.6. Slightly more than one-third (37.7%) of the 409 patients with INR data had TTR ≥ 65%. Patients who met this cutoff had a lower cumulative 5-year stroke incidence than those with suboptimal TTR (6.9% vs 15.1%; P = .01).

Among patients discharged on warfarin, landmark analysis at 4 months showed a trend for higher cumulative incidence of stroke in the 62.3% of patients on dual antiplatelet therapy (DAPT) compared with those not on dual therapy (15.1% vs 6.7%; P = .052). Bleeding also appeared elevated in the DAPT group (14.7% vs 8.7%; P = .10).

“[Oral anticoagulation] is underused presumably due to physicians’ concern for bleeding complications,” the researchers comment, noting that prior studies have shown hemorrhagic risk rises up to 6 times when warfarin is added to clopidogrel and aspirin. “Considering the increased risk of major bleeding in the setting of triple therapy, duration of DAPT should be as short as possible. To reduce stroke risk, we should focus more on optimizing [oral anticoagulation] rather than prolonging DAPT,” they advise, adding that omitting aspirin from the equation “may be an attractive alternative to triple therapy.”

Anticoagulation Comes Before DAPT

Marco Valgimigli, MD, PhD, of the University of Ferrara (Ferrara, Italy), told TCTMD in an email that “the magnitude of the problem here seems more than what I expected.”

Current recommendations pushing for triple therapy are based on rather weak evidence from meta-analyses of observational studies, he said. “[C]linicians well know that triple therapy is a problem; it is a must to keep it as short as possible, and many patients would hardly tolerate any triple at all. So the underuse reflects the real difficulty of applying these recommendations in clinical practice more than laziness or distraction paid by clinicians, I think.”

Previous retrospective studies have observed “keeping INR in the low range saves bleeding and still protects patients from stroke. This retrospective analysis would really suggest the opposite, as low TTR does not seem protective against stroke,” he noted. Reflecting the “difficulties of managing these complicated patients,” the current findings suggest that oral anticoagulation should be titrated similar to how it is in non-PCI patients, he said.

Novel oral anticoagulants may change things, Dr. Valgimigli commented. “The reality is that managing patients taking vitamin K antagonists is not easy as INR keeps jumping high and low, and the belief that we can maintain [a stable INR] over time is quite a dream,” he said, adding that the newer drugs are “clearly safer.”

Clinicians should bear in mind, Dr. Valgimigli emphasized, that stroke prevention in this population is the prevailing issue, so curtailing DAPT should be considered. “I frequently see interventional cardiologists pushing for stopping oral anticoagulation in these patients and preferring the full DAPT regimen. I personally believe this is a mistake,” he said. “Oral anticoagulation should continue and DAPT [should be] shortened as much as possible.”

 

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Source:
Goto K, Nakai K, Shizuta S, et al. Anticoagulant and antiplatelet therapy in patients with atrial fibrillation undergoing percutaneous coronary intervention. Am J Cardiol. 2014;Epub ahead of print.

 

 

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