TIMI myocardial perfusion frame count: A new method to assess myocardial perfusion and its predictive value for short‐term prognosis

Objectives: We sought to develop a new quantitative method to evaluate the degree of myocardial perfusion. Background: Currently available methods for assessing myocardial perfusion, both TIMI myocardial perfusion grading (TMPG) and myocardial blush grading (MBG), are subjective. Methods: TIMI Myocardial Perfusion Frame Count (TMPFC), an objective method that measures the filling and clearance of contrast in the myocardium using cine‐angiographic frame‐counting, was developed to quantify myocardial perfusion. Myocardial perfusion of 45 normal coronary arteries in 15 patients, and 137 culprit arteries in 137 patients immediately after primary angioplasty, was successfully assessed with TMPFC. Results: The mean TMPFC in the normal arteries was 83.47 ± 17.96 frames (95% CI: 78.07 frames ≤ TMPFC ≤ 88.86 frames). Therefore, TMPFC < 90 frames, a value representing the upper bound of the 95% CI for the TMPFC observed in normal arteries, was defined as normal myocardial perfusion. In 137 culprit arteries, the mean TMPFC values after primary angioplasty for the right coronary artery (RCA), left anterior descending artery (LAD), and left circumflex artery (LCX) were 141 ± 82.6, 112 ± 80.3, and 102 ± 37.5 frames, respectively. Patients with suboptimal myocardial perfusion (ex: TMPG ≤ 2 or MBG ≤ 2 grade) had higher levels of TMPFC. Furthermore, multivariate analysis shows that the TMPFC was an independent predictor for 30‐day (P = 0.0261) and 6‐month incidence of MACE (P = 0.0207). Conclusions: TMPFC is a quantitative index for the assessment of myocardial perfusion; it allows quantification of TMPG and may serve as a discerning tool to predict prognosis in patients undergoing primary angioplasty.