Fractional myocardial flow reserve (FFRmyo) after coronary intervention asa predictor of chronic restenosis

The angiographic assessment of coronary stenosis has many limitations, espe cially after coronary intervention. To determine the physiologic significan ce of such lesions, we measured the mean translesional pressure gradients a t rest (P1), those during hyperemia induced by intracoronary administration of papaverine (12 mg in the left and 8 mg in the right coronary artery) (P 2), and fractional myocardial flow reserve (FFRmyo) which is derived from t he ratio of the mean distal coronary pressure and aortic pressure during hy peremia. Our objective was to determine the relations among P1, P2, and FFR myo and restenosis as potential predictors of chronic restenosis. The group ed study consisted of 32 patients with ischemic heart disease scheduled to undergo intervention. The distal coronary pressure was measured using a 0.0 14 inch pressure monitoring wire (Pressure Guide (TM), Radi Medical Systems , Uppsala, Sweden). The guidewire was advanced through the lesional segment . The mean percent diameter stenosis (%DS) was 67.9 +/- 13.3% before interv ention and 22.9 +/- 15.3% after intervention. The mean P2 (9.9 +/- 5.3 mmHg ) was significantly higher than the mean P1 (4.5 +/- 3.6 mmHg; p < 0.0001). There was no correlation of P1, P2 or FFRmyo with the %DS after interventi on. Follow-up angiography (after 6 months) performed on all patients reveal ed restenosis (%DS greater than or equal to 50%) in four patients (12.5%). There was no correlation between P1 and the %DS at the follow-up angiograph y, but the relation between P2, FFRmyo and the %DS at the follow-up angiogr aphy was significant (r = 0.599, p < 0.01; r = 0.703, p < 0.0001, respectiv ely). As a measurement of P2, FFRmyo is useful for the determination of the endpoint of intervention in consideration of prevention of restenosis. A n ew endpoint may be established after further evaluation in a greater number of patients.