Comparison of Current and Novel ECG-Independent Algorithms for Resting Pressure Derived Physiologic Indices

Recently, instantaneous wave-free ratio (iFR) or diastolic pressure-ratio (dPR) have been used in practice. For these indices, the reliability of electrocardiography (ECG)-independent algorithm for pressure-only data is essential. The current study sought to compare the current to a new ECG-independent algorithm for calculating resting physiologic indices. The main purpose of developing a new ECG-independent algorithm was to raise the detection rates over the entire heart cycle despite irregular heartbeats. Both iFR and dPR were calculated from resting pressure tracings using current and new algorithms by a core laboratory in 975 vessels (393 patients). The diagnostic performance of resting physiologic indices with a new algorithm to predict fractional flow reserve (FFR) was compared with the current algorithm. Both algorithms provided nearly identical values of iFR or dPR without systemic bias. iFR and dPR, which were calculated using current and new ECG-independent algorithms, provided comparable discrimination ability and diagnostic performance to predict functionally significant stenosis defined by FFR≤0.80. However, detection rates of the new algorithm were significantly higher than current algorithm in the patients with irregular heartbeats (for per patient [59.5% vs. 83.8%] and per unit-heartbeats analysis [84.3% vs. 90.3%]), such as arterial fibrillation or multiple premature ventricular contractions.