Nasir Rahman1, Jamshed Ali1, Ghufran Adnan1

1Aga Khan University Hospital Karachi Pakistan, Karachi, Pakistan

Background:
Fractional flow Reserve (FFR) is the standard method to evaluate the functional significance of epicardial coronary stenosis in cases of intermediate coronary lesions. Instantaneous wave-free ratio (iFR) is a physiological index of coronary stenosis severity which does not need adenosine administration for maximal hyperemia, and has been proven to be non-inferior to FFR. Through this study we aimed to assess long-term clinical outcomes of patients in whom intervention of coronary lesions was deferred due to negative FFR and iFR and to identify factors associated with deferred target lesion failure.

Method(s):
Retrospective analysis of a cohort of 345 patients in whom coronary revascularization was deferred due to a negative FFR or iFR was done for assessment of hemodynamic significance of the intermediate coronary stenoses at the Aga Khan University Hospital, Karachi, from January 2012 to January 2020. The data was collected from medical records of these patients.

Result(s):
Between the above said period, a total of 515 patients with intermediate coronary lesions underwent functional physiological assessment. Among these, 345 patients had negative FFR (≥ 0.80) or negative iFR (≥0.90) and revascularization was deferred. These patients were included in our study. 71% of them were males with mean age of 62 ±11. Mean ejection fraction was 52%. Patient presentation with ACS was 44% and with stable angina was 56%. In ACS group, 67% presented with Non-ST elevation MI, 27% with Unstable angina and 6 % with ST elevation MI. The most common artery in which FFR or iFR was done LAD (53%). Mean FFR value was 0.87 ± .04 and Mean iFR value was 0.93 ± .03. Multivessel disease was present in 69%. Mean vessel stenosis percentage was 61 ± 6. Post FFR revascularization of other arteries was done in 47% of patients. The most prescribed medications on discharge was statin (99%) Mean follow up period was 40±9 months.  Major adverse cardiovascular events occurred in 9 patients (2.6%) and target vessel revascularization was done in 12 patients (3.47%). Multivariable cox regression analysis showed age, multivessel disease and percentage of stenosis independent predictor of adverse outcomes and target vessel revascularization.

Conclusion(s):
Through this study we found out that on the basis of long term major cardiac adverse cardiac events and target lesion revascularization rate, it can be concluded that intermediate coronary lesions can safely be deferred on the basis of FFR or iFR. Age, multivessel disease and percentage of stenoses were found to be independent predictors for adverse cardiac outcomes and target vessel revascularization.