BACKGROUND: Stenotic flow reserve (SFR) derived from quantitative coronary angiography (QCA) has been correlated with myocardial ischemia as determined by pharmacological stress echocardiography. However, the diagnostic accuracy of SFR in predicting functionally significant coronary stenosis as assessed by the gold standard, fractional flow reserve (FFR), has not been previously characterized.
METHODS: Patients who underwent coronary angiography and FFR assessment between January 2010 and February 2012 in a single tertiary center were retrospectively assessed. QCA parameters such as minimal lumen diameter (MLD), lesion length, diameter stenosis (DS), SFR, turbulent resistance (TR) and Poiseuille resistance (PR) were assessed. Significant FFR was defined as FFR â‰¤0.8. The diagnostic accuracy of QCA parameters to predict significant FFR was assessed by independent t-test and receiver operator characteristic (ROC) curve. Statistical significance was defined as P value of 50% (AUC =0.64).
RESULTS: Using a retrospectively determined optimal cut-off value of 3.51, the sensitivity of stenotic-flow-reserve was modest at 56% with good specificity of 81%. DS >50% had a sensitivity of 47% and specificity of 82% in predicting significant FFR.
CONCLUSIONS: There was incremental predictive value when SFR was added to DS >50% on integrated discrimination improvement index (IDI =0.103, P<0.001) and net reclassification index (NRI =0.72, P50% for predicting significant FFR.