Diagnostic accuracy of diastolic pressure ratio using a pressure microcatheter for intracoronary physiological assessment.

Recently, instantaneous wave-free ratio (iFR) has emerged as an alternative to the fractional flow reserve (FFR) for intracoronary physiological assessment. Although all diastolic resting indices are reportedly identical to the iFR, limited data exist on diastolic pressure ratio (dPR) measured using a microcatheter (dPRmicro). This study aimed to evaluate the diagnostic accuracy of dPRmicro compared to FFR measured using a microcatheter (FFRmicro) in real-world practice for intracoronary physiological assessment. This was a single-center, retrospective, observational study. We identified 103 consecutive suspected angina pectoris patients (107 lesions) who underwent dPRmicro and FFRmicro measurement using the Navvus® catheter at Takasaki Heart Hospital from March 2019 to June 2019. A total of 103 lesions in 103 patients were finally included in the study. The mean FFRmicro and dPRmicro values were 0.80 and 0.88, respectively. With an FFRmicro ≤ 0.80, the dPRmicro showed a diagnostic accuracy of 79.6%, sensitivity of 74.6%, specificity of 87.5%, positive predictive value of 90.4%, and negative predictive value of 68.6%. The area under the receiver operating characteristic (ROC) curve was 0.894 (95% confidence interval, 0.833-0.956), and the optimal cut-off value for dPRmicro derived from the ROC analysis was 0.90. dPRmicro and FFRmicro values were discordant in 21/103 cases (20.4%). As a multivariable logistic regression analysis was performed, the male sex (vs. female) had a statistically significant association with a dPRmicro-FFRmicro discordance (OR 4.91; 95% CI, 1.04-23.0; P = 0.044). No other factors were found to be significantly associated with the discordance. In conclusion, dPRmicro measured using a microcatheter had good diagnostic accuracy and correlation with FFRmicro, hence, it can be useful for making revascularization decisions. However, re-studies in larger populations will be needed to better understand the properties of diastolic resting index measured using a microcatheter in clinical settings.