Risk of Paradoxical Embolism (RoPE)-Estimated Attributable Fraction Correlates With the Benefit of Patent Foramen Ovale Closure: An Analysis of 3 Trials

Abstract

Background and Purpose: In patients with cryptogenic stroke and patent foramen ovale (PFO), the Risk of Paradoxical Embolism (RoPE) Score has been proposed as a method to estimate a patient-specific "PFO-attributable fraction" - the probability that a documented PFO is causally-related to the stroke, rather than an incidental finding. The objective of this research is to examine the relationship between this RoPE-estimated PFO-attributable fraction and the effect of closure in 3 randomized trials. Methods: We pooled data from the CLOSURE-I (Evaluation of the STARFlex Septal Closure System in Patients With a Stroke and/or Transient Ischemic Attack due to Presumed Paradoxical Embolism through a Patent Foramen Ovale), RESPECT (Randomized Evaluation of Recurrent Stroke Comparing PFO Closure to Established Current Standard of Care Treatment), and PC (Clinical Trial Comparing Percutaneous Closure of Patent Foramen Ovale [PFO] Using the Amplatzer PFO Occluder With Medical Treatment in Patients With Cryptogenic Embolism) trials. We examine the treatment effect of closure in high RoPE score (≥7) versus low RoPE score (<7) patients. We also estimated the relative risk reduction associated with PFO closure across each level of the RoPE score using Cox proportional hazard analysis. We estimated a patient-specific attributable fraction using a PC trial-compatible (9-point) RoPE equation (omitting the neuroradiology variable), as well as a 2-trial analysis using the original (10-point) RoPE equation. We examined the Pearson correlation between the estimated attributable fraction and the relative risk reduction across RoPE strata. Results: In the low RoPE score group (<7, n=912), the rate of recurrent strokes per 100 person-years was 1.37 in the device arm versus 1.68 in the medical arm (hazard ratio, 0.82 [0.42-1.59] P=0.56) compared with 0.30 versus 1.03 (hazard ratio, 0.31 [0.11-0.85] P=0.02) in the high RoPE score group (≥7, n=1221); treatment-by-RoPE score group interaction, P=0.12. The RoPE score estimated attributable fraction anticipated the relative risk reduction across all levels of the RoPE score, in both the 3-trial (r=0.95, P<0.001) and 2-trial (r=0.92, P<0.001) analyses. Conclusions: The RoPE score estimated attributable fraction is highly correlated to the relative risk reduction of device versus medical therapy. This observation suggests the RoPE score identifies patients with cryptogenic stroke who are likely to have a PFO that is pathogenic rather than incidental.