title: Frame counting improves the assessment of post-reperfusion microvascular patency by TIMI myocardial perfusion grade: Evidence from cardiac magnetic resonance imaging.
abstract: BACKGROUND
  Quantitative modification of TIMI myocardial perfusion grade (TMPG) by the method of frame counting may improve its sensitivity and the false negative rate for post-reperfusion microvascular dysfunction (MVD) in ST segment-elevated myocardial infarction (STEMI) patients.
  
  
  METHODS
  The durations of contrast-washout from infarction area of 139 patients were measured by counting the cine-frame numbers between the appearance and disappearance of myocardial blush. The achieved new index, TMP Frame Counting (TMP-FC) was referenced by cardiac magnetic resonance, by which MVD was defined as microvascular obstruction on gadolinium late-enhancement imaging.
  
  
  RESULTS
  Median TMP-FC differed significantly between patients with and without MVD (126 frames, IQR 105-160 vs. 86 frames, IQR 75-100, p<0.001). By receiver-operating characteristic analysis, the cutoff of TMP-FC at ≥ 95.5 frames represented an independent predictor of MVD (OR=11.61, p<0.001). TMP-FC had similar specificity (75%) and positive predictive value (88%), but significantly improved sensitivity (85.3%) and negative predictive value (70.2%) for MVD compared with TMPG (88.6%, 86.5%, 33.7% and 38.2%, respectively) and other traditional angiographic assessments, leading to a better overall accuracy (area under the curve: 0.801 compared with 0.612 from TMPG, p<0.001) for the evaluation of microvascular patency. TMP-FC was positively correlated with MVD extent (r=0.5, p<0.001). Abnormal TMP-FC was associated with larger infarction size (28.67 ± 13.72% vs. 16.51 ± 10.68% of left ventricular mass, p<0.001) and lower LVEF (49.37 ± 11.06% vs. 56.84 ± 9.72%, p<0.001).
  
  
  CONCLUSIONS
  Frame counting can improve the accuracy of TMPG for MVD. Moreover, TMP-FC is correlated with the degree of MVD and cardiac detriments, which is useful for risk stratification.
authors.affiliation: Department of Cardiology, Renji Hospital, School of Medicine, Shanghai Jiao Tong University, China.
authors.forename: Heng
authors.initials: H
authors.lastname: Ge
authors.affiliation: Department of Cardiology, Renji Hospital, School of Medicine, Shanghai Jiao Tong University, China.
authors.forename: Song
authors.initials: S
authors.lastname: Ding
authors.affiliation: Department of Radiology, Renji Hospital, School of Medicine, Shanghai Jiao Tong University, China.
authors.forename: Dongaolei
authors.initials: D
authors.lastname: An
authors.affiliation: Department of Cardiology, Renji Hospital, School of Medicine, Shanghai Jiao Tong University, China.
authors.forename: Zheng
authors.initials: Z
authors.lastname: Li
authors.affiliation: Center for Biomedical Imaging Research, Department of Biomedical Engineering, Tsinghua University, China.
authors.forename: Haiyan
authors.initials: H
authors.lastname: Ding
authors.affiliation: Department of Cardiology, Renji Hospital, School of Medicine, Shanghai Jiao Tong University, China.
authors.forename: Fan
authors.initials: F
authors.lastname: Yang
authors.affiliation: Department of Cardiology, Renji Hospital, School of Medicine, Shanghai Jiao Tong University, China.
authors.forename: Lingcong
authors.initials: L
authors.lastname: Kong
authors.affiliation: Department of Radiology, Renji Hospital, School of Medicine, Shanghai Jiao Tong University, China.
authors.forename: Jianrong
authors.initials: J
authors.lastname: Xu
authors.affiliation: Department of Cardiology, Renji Hospital, School of Medicine, Shanghai Jiao Tong University, China. Electronic address: pujun310@hotmail.com.
authors.forename: Jun
authors.initials: J
authors.lastname: Pu
authors.affiliation: Department of Cardiology, Renji Hospital, School of Medicine, Shanghai Jiao Tong University, China. Electronic address: heben@medmail.com.cn.
authors.forename: Ben
authors.initials: B
authors.lastname: He
mesh_terms: D017023:Coronary Angiography; D003325:Coronary Care Units; D003326:Coronary Circulation / Q000502:physiology*; D004562:Electrocardiography; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000379:methods*; D019028:Magnetic Resonance Imaging, Cine / Q000379:methods*; D008297:Male; D008833:Microcirculation / Q000502:physiology*; D008875:Middle Aged; D009203:Myocardial Infarction / Q000175:diagnosis* / Q000503:physiopathology / Q000628:therapy; D015425:Myocardial Reperfusion / Q000379:methods*; D011446:Prospective Studies; D015203:Reproducibility of Results; D013997:Time Factors
keywords: Angiographic assessment; CMR; Microvascular dysfunction; Reperfusion; STEMI