Introduction: The Risk of Paradoxical Embolism (RoPE) Score can disaggregate patients with cryptogenic stroke (CS) and patent foramen ovale (PFO) into those who are more likely to have a pathogenic PFO (high RoPE score) than an incidental PFO (low RoPE score). Those with higher RoPE scores have a lower risk of recurrent stroke and different recurrence predictors compared to those with low RoPE scores.
Hypotheses: Patients with high RoPE scores benefit more from PFO closure than patients with low RoPE scores. Patients with high RoPE scores and risk factors for recurrence should benefit even more.
Methods: The RoPE score was created from a database of CS patients with known PFO status to estimate stratum-specific PFO-attributable fraction and recurrence rates. Variables that predict stroke recurrence in high RoPE score groups (atrial septal aneurysm, history of stroke/TIA prior to index event) were added – the “RoPE Recurrence Score.” Using pooled individual patient data from all 3 RCTs of PFO closure vs. medical therapy (ITT populations; stroke outcome) we tested the ability of the scores to predict the heterogeneity of response to assigned treatment.
Results: The mean RoPE score was significantly higher (6.8 vs. 6.3) with smaller variance (Stdev 1.5 vs. 1.9) in the pooled RCT population than in the original RoPE cohort (p<0.0001). Hazard ratios favoring closure were 0.82 (0.42-1.59, p=0.56) in the low RoPE score (<7) group and 0.31 (0.11-0.85, p=0.02) in the high RoPE score (≥7) group but the interaction p-value was not significant (p=0.12). The RoPE Recurrence score did not improve the prediction of treatment response (low score HR=0.65 (0.31-1.37), p=0.26; high score HR=0.58 (0.26-1.26), p=0.17; interaction p=0.82).
Conclusion: As expected, the HR favoring closure trended lower in the high RoPE score group in the RCTs but missed statistical significance. The RoPE Recurrence score did not improve the prediction. This may be due to the narrow distribution of relatively high RoPE scores amongst RCT patients and so a low power to detect heterogeneity of treatment effect. Given that PFO closure can only prevent PFO-related recurrences, the treatment effect may also have been obscured by including recurrent strokes with non-PFO-related mechanisms.