Abstract 11996: The Impact of Left Ventricular Diastolic Dysfunction on Instantaneous Wave-Free Ratio in Intermediate Coronary Stenosis

Abstract

Background: Instantaneous wave-free ratio (iFR) is a new vasodilator-free index of the functional severity of coronary stenosis and reported to have a similar feature to coronary flow reserve (CFR) that is considered to reflect not only resistances of an epicardial stenosis but also microvascular resistances in myocardium. Previous studies reported that CFR was impaired in patients with left ventricular (LV) diastolic dysfunction which is thought to have an impact on microvascular circulation. However, there was no report examining the impact of LV diastolic dysfunction on iFR. Accordingly, the purpose of this study was to assess the relationship between iFR and LV diastolic dysfunction in comparison with fractional flow reserve (FFR). Method and Results: We examined consecutive 76 patients (with 107 stenosis) whose iFR, FFR and E/e’ were measured simultaneously. Patients with hemodialysis or left ventricular hypertrophy (defined as left ventricular mass index more than 116g/m2 (male) or 96g/m2 (female) in echocardiography) were excluded. LV diastolic dysfunction in the present study was defined as E/e’ more than 15. The mean age of patients with LV diastolic dysfunction (n=18, mean E/e’=19.3 ± 6.3) was higher than patients without LV diastolic dysfunction (n=58, mean E/e’= 10.1 ± 6.2). Other patients’ characteristics are shown in table 1. The mean iFR values in patients with LV diastolic dysfunction was significantly lower than that in patients without LV diastolic dysfunction, despite no significant differences were observed in the mean FFR values and % diameter stenosis (Table 2). iFR showed negative correlation with E/e’ (r=0.31, p=0.0012) (Figure 1), whereas, there was no correlation between FFR and E/e’ (data not shown). Conclusion: Our present results suggested that LV diastolic dysfunction affect the iFR values, but not FFR, in intermediate coronary stenosis. In patients with LV dysfunction, iFR may overestimate the severity of coronary stenosis.