Myocardial Blood Flow Quantified by Low-Dose Dynamic CT Myocardial Perfusion Imaging Is Associated with Peak Troponin Level and Impaired Left Ventricle Function in Patients with ST-Elevated Myocardial Infarction

OBJECTIVE: To investigate the association of myocardial blood flow (MBF) quantified by dynamic computed tomography (CT) myocardial perfusion imaging (MPI) with troponin level and left ventricle (LV) function in patients with ST-segment elevated myocardial infarction (STEMI). MATERIALS AND METHODS: Thirty-five STEMI patients who successfully had undergone reperfusion treatment within 1 week of their infarction were consecutively enrolled. All patients were referred for dynamic CT-MPI. Serial high-sensitivity troponin T (hs-TnT) levels and left ventricular ejection fraction (LVEF) measured by echocardiography were recorded. Twenty-six patients with 427 segments were included for analysis. Various quantitative parameters derived from dynamic CT-MPI were analyzed to determine if there was a correlation between hs-TnT levels and LVEF on admission and again at the 6-month mark. RESULTS: The mean radiation dose for dynamic CT-MPI was 3.2 ± 1.1 mSv. Infarcted territories had significantly lower MBF (30.5 ± 7.4 mL/min/100 mL versus 73.4 ± 8.1 mL/min/100 mL, p < 0.001) and myocardial blood volume (MBV) (2.8 ± 0.9 mL/100 mL versus 4.2 ± 1.1 mL/100 mL, p = 0.044) compared with those of reference territories. MBF showed the best correlation with the level of peak hs-TnT (r = −0.682, p < 0.001), and MBV showed a moderate correlation with the level of peak hs-TnT (r = −0.437, p = 0.026); however, the other parameters did not show any significant correlation with hs-TnT levels. As for the association with LV function, only MBF was significantly correlated with LVEF at the time of admission (r = 0.469, p = 0.016) and at 6 months (r = 0.585, p = 0.001). CONCLUSION: MBF quantified by dynamic CT-MPI is significantly inversely correlated with the level of peak hs-TnT. In addition, patients with lower MBF tended to have impaired LV function at the time of their admission and at 6 months.

Difference in myocardial strain between obstructive hypertrophy cardiomyopathy and nonobstructive hypertrophy cardiomyopathy / 上海交通大学学报（医学版）

Objective · To investigate the difference in myocardial strain of left ventricle between obstructive hypertrophy cardiomyopathy (HCM) and nonobstructive HCM. Methods · Cardiac magnetic resonance imaging (MRI) exam was performed on 48 sequential enrolled patients with HCM (18 with obstructive HCM, and 30 with nonobstructive HCM), whose left ventricular ejection fractions (LVEF) were over 50%. Twenty-five healthy volunteers were examined as normal controls. Global longitudinal strain (GLS), global radial strain (GRS), global circumferentialstrain (GCS), LVEF, left ventricular end diastolic volume (LVEDV), left ventricularmass (LVM), left ventricular end diastolic volume index (LVEDVI), and left ventricular mass index (LVMI) were collected and compared. Radial strain, circumferential strain and peak radial displacement were also measured in medial segment of left ventricle according to American Heart Association (AHA) 17-segment model. Results · ① LVEF of the patients with obstructive HCM was bigger than those of nonobstructive HCM patients and control group (P<0.05). LVM and LVMI of the HCM groups were bigger than those of control group (P<0.01). ② Left ventricle GLS, GRS, and GCS significantly decreased in the patients with nonobstructive HCM compared to those with obstructive HCM (P<0.05). The three parameters of two HCM groups were significantly lower than those of healthy volunteers (P<0.05). ③ Compared with obstructive HCM patients,the segmental parameters of left ventricule, the medial segment circumferential strain and radial strain of nonobstructive HCM patients significantly decreased (P<0.05), and the two parameters of both HCM groups were lower than those in healthy volunteers. Compared with obstructive HCM patients and healthy volunteers, peak radial displacement of left ventricule medial segment in nonobstructive HCM witnessed a significant decrease, while no significant difference was observed between obstructive HCM patients and healthy volunteers. Conclusion · In the LVEF preserved HCM patients, the myocardial strain of left ventricle in nonobstructive HCM patients decrease significantly than that in obstructive HCM patients, which may result in the different clinical outcomes intwo types of HCM patients. It is suggested that the myocardial strain is more sensitive than ejection fraction in the evaluation of myocardial performance of HCM patients.