New formula identifies candidates for PFO closure to prevent recurrent stroke
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A new classification system accurately predicted which patients with ischemic stroke of unknown original might benefit from patent foramen ovale closure.
“While PFO closure has been found to reduce the overall risk of recurrent stroke, it had previously been unclear whether this approach would be beneficial for every individual stroke patient, or if other therapies might be more appropriate in certain cases,” David M. Kent, MD, director of the Predictive Analytics and Comparative Effectiveness (PACE) Center at Tufts Medical Center, said in a press release. “Our classification system can help predict with great precision which of these patients would benefit from PFO closure and which might be effectively treated with medical therapy alone.”
Kent and colleagues pooled individual patient data from 3,740 patients from six randomized trials comparing PFO closure plus medical therapy to medical therapy alone for recurrent stroke prevention.
Two classification systems
Each patient was given a Risk of Paradoxical Embolism (RoPE) score of 1 to 10, in which higher numbers signified younger age and absence of vascular risk factors, and categorized each patient as probable, possible or unlikely that their stroke was caused by a PFO. The latter categorization, the PFO-Associated Stroke Causal Likelihood (PASCAL) Classification System, combined the RoPE score with the presence or absence of high-risk PFO features such as an atrial septal aneurysm or a large shunt.
At 57 months, the annualized incidence of stroke was 1.09% in those assigned medical therapy alone and 0.47% in those assigned PFO closure plus medical therapy (adjusted HR = 0.41; 95% CI, 0.28-0.6), according to the researchers.
Patients with low RoPE scores had higher HRs for stroke (HR = 0.61; 95% CI, 0.37-1) than those with high RoPE scores (HR = 0.21; 95% CI, 0.11-0.42; P for interaction = .02), Kent and colleagues wrote.
In turn, patients categorized by PASCAL as unlikely (HR = 1.14; 95% CI, 0.53-2.46) had higher HRs for stroke than those categorized as possible (HR = 0.38; 95% CI, 0.22-0.65) or probable (HR = 0.1; 95% CI, 0.03-0.35; P for interaction = .003), according to the researchers.
The 2-year absolute risk reduction for stroke due to PFO closure was 2.1% in both the possible and probable groups, but –0.7% in the unlikely group, Kent and colleagues found. They also found that the unlikely group was more likely to have device-related adverse events from PFO closure and atrial fibrillation beyond 45 days after randomization to PFO closure than the possible and probable groups.
“This classification system is much more reliable than any previous model in determining which patients are most likely to benefit from having their PFO closed,” Kent said in the release. “We believe this formula will translate to clinically meaningful changes to help reduce recurrent strokes, prevent unnecessary procedures and change practice for this patient population. The dramatic results we see in this project should encourage other researchers to apply multivariable predictive methods for identifying subgroups to provide better personalized evidence from clinical trials.”
‘Critical evidence’
“The findings of this study by Kent et al provide critical evidence that can immediately influence the clinical evaluation and care of patients with cryptogenic stroke and PFO,” Robert W. Yeh, MD, director of the Smith Center for Outcomes Research in Cardiology at Beth Israel Deaconess Medical Center and associate professor of medicine at Harvard Medical School, and Doreen DeFaria Yeh, MD, associate director of the MGH Adult Congenital Heart Disease Program and co-director of the MGH Cardiovascular Disease and Pregnancy Program at Massachusetts General Hospital, wrote in a related editorial. “Rigorous analysis of individual patient data from six well-conducted randomized clinical trials meets the standard of being among the highest levels of evidence to date. The fact that the PASCAL and RoPE scores were developed based on clinical plausibility and refined in separate observational databases helps overcome any notion that these findings might be ‘overfit.’ More important, the applicability of the evidence to individual patients could potentially influence clinical practice.”
References:
- New Formula Predicts with High Accuracy Which Patients with Recurring Stroke Would Benefit from PFO Closure. Posted Dec. 14, 2021. Accessed Dec. 15, 2021.
- Yeh RW, et al. JAMA. 2021;doi:10.1001/jama.2021.21317.
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