Correlation and Relative Prognostic Value of Fractional Flow Reserve and Pd/Pa of Nonculprit Lesions in ST-Segment-Elevation Myocardial Infarction

Background: The applicability of resting indices to guide noninfarct-related artery revascularization in ST-elevation myocardial infarction is unknown. Methods: We analyzed the correlation and prognostic value of fractional flow reserve (FFR) and resting distal coronary to aortic pressure ratio (Pd/Pa) in all patients of the Compare-Acute trial in whom, after successful primary percutaneous coronary intervention, the noninfarct-related artery was interrogated by both and treated medically. The treating cardiologist was blinded to these values. The primary end point was the composite of target vessel (interrogated noninfarct-related artery) related nonfatal target vessel myocardial infarction and target vessel repeat revascularization at 36 months. Results: Five hundred seventeen patients (665 vessels) were included. On receiver-operating characteristic analysis, the optimal Pd/Pa cut off for FFR≤0.80 was 0.905 (C statistic: 0.894). The diagnostic accuracy of Pd/Pa was 80.15% (95% CI, 76.91%-83.12%) with respect to FFR. During the 36-month follow-up, 130 target vessel revascularization and 14 target vessel myocardial infarction occurred. FFR and Pd/Pa had a diagnostic accuracy to predict these events of 62.86% (95% CI, 59.06%-66.54%) and 56.84% (95% CI, 52.98%-60.64%), respectively (P=0.20). When they were discrepant, FFR was significantly better than Pd/Pa in identifying which vessels could be safely deferred (P=0.048). Conclusions: Immediately after successful primary percutaneous coronary intervention, resting Pd/Pa has a diagnostic accuracy of 80% with respect to FFR measured in the noninfarct-related artery. FFR is not significantly superior in predicting target vessel myocardial infarction and target vessel revascularization during 36 months of follow-up but, in case FFR and Pd/Pa are discrepant, FFR is superior in identifying which nonculprit vessels can be safely deferred. Registration: URL: https://www.clinicaltrials.gov; Unique identifier: NCT01399736.