The iFR-SWEDEHEART Reclassification Substudy
Study Questions:
What is the impact on reclassification of treatment strategy following instantaneous wave-free ratio (iFR) and fractional flow reserve (FFR)?
Methods:
The investigators conducted a substudy from the iFR-SWEDEHEART (Instantaneous Wave-Free Ratio Versus Fractional Flow Reserve in Patients With Stable Angina Pectoris or Acute Coronary Syndrome) trial to compare reclassification patterns between iFR and FFR. The iFR-SWEDEHEART study randomized 2,037 participants with stable angina or acute coronary syndrome to treatment guided by iFR or FFR. Interventionalists entered the preferred treatment (optimal medical therapy [OMT], percutaneous coronary intervention [PCI], or coronary artery bypass grafting [CABG]) on the basis of coronary angiograms, and the final treatment decision was mandated by the iFR/FFR measurements. Event rates were calculated with the Kaplan-Meier method, and distributions between groups were compared with the log-rank test.
Results:
In the iFR/FFR (n = 1,009/n =1,004) populations, angiogram-based treatment approaches were similar (p = 0.50) with respect to OMT (38%/35%), PCI of one (37%/39%), 2 (15%/16%), and three vessels (2%/2%) and CABG (8%/8%). iFR and FFR reclassified 40% and 41% of patients, respectively (p = 0.78). The majority of reclassifications were conversion of PCI to OMT in both the iFR/FFR groups (31.4%/29.0%). Reclassification increased with increasing number of lesions evaluated (odds ratio per evaluated lesion for FFR: 1.46 [95% confidence interval, 1.22-1.76] vs. iFR: 1.37 [95% confidence interval, 1.18-1.59]). Reclassification rates for patients with one, two, and three assessed vessels were 36%, 52%, and 53% (p < 0.01).
Conclusions:
The authors concluded that reclassification of treatment strategy of intermediate lesions was common and occurred in 40% of patients with iFR or FFR.
Perspective:
This study reports that both iFR and FFR reclassified 40% of the a priori angiogram-based treatment strategies with no significant differences in treatment strategy reclassifications between iFR and FFR. The majority of reclassifications were conversions of PCI into OMT with both measurement modalities. It should be noted that this substudy was not powered to detect differences in outcome between iFR and FFR with respect to reclassification status. Additional studies are indicated to assess longer-term outcomes in relation to the different physiology methods and post-physiology treatment strategies.
Keywords: Acute Coronary Syndrome, Angina, Stable, Coronary Angiography, Coronary Artery Bypass, Coronary Artery Disease, Fractional Flow Reserve, Myocardial, Myocardial Ischemia, Percutaneous Coronary Intervention, Secondary Prevention, Treatment Outcome
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