Correlation between myocardial infarction activity assessed by cardiac magnetic resonance imaging and the evolution of cardiac function after PCI

Objective:To investigate the correlation of cardiac magnetic resonance imaging(MRI)in the assessment of myocardial activity in patients with myocardial infarction and the outcome of cardiac function after PCI.Methods:30 patients with myocardial infarction(MI)who had complete clinical and imaging data from July 2016 to December 2018 after PCI were analyzed retrospectively.MR and echocardiogram were performed before and 6 months after PCI,and the parameters related to left ventricular function were measured by post-processing software of MRI workstation.The left ventricular transmural degree of CMR late gadolinium enhancement was compared with the left ventricular wall motion degree of 6-month echocardiography as a standard to judge the viable myocardium.Result:There were 193 left ventricular segmental abnormalities in 30 cases,including 121 viable myocardium and 72 non viable myocardium in CMR-LGE before operation.Six months after PCI,echocardiography showed that 125 of 193 abnormal segments of left ventricle detected by CMR-LGE before PCI were viable myocardium and 68 were non viable myocaridium.The sensitivity and specificity of CMR-LGE to determinate of viable myocardium were 92.0%and 91.1%respectively.The larger the non-viable myocardial area of the left ventricular wall,the worse the recovery of wall motion ability,and there was a negative correlation between them(r=0.416,P<0.05).The first-pass perfusion time in CMR-LEG region was significantly longer than that in normal myocardial region(4.85(+)1.51)s and(3.79(+)1.73)s,respectively.The difference was statistically significant(t=5.191,P<0.05).Conclusion:MRI can evaluate the myocardial activity of myocardial infarction,reflect the range of viable myocardium,and provide imaging basis for clinical treatment and prognosis.

Activation of epidermal growth factor receptor mediates myocardial ischemia/reperfusion arrhythmias in anaesthetized rats

Objectives Epidermal growth factor receptor （EGFR）is a receptor protein tyrosine kinase and plays a critical role in the development and function of the heart.Previous studies have demonstrated that EGFR is involved in regulating electrical excitability of the heart.The present study was designed to investigate whether EGFR activation would mediate myocardial arrhythmias induced by ischemia/reperfu- sion in anaesthetized rats.Methods and results Myocardial ischemia/reperfusion arrhythmias were induced by 10 min ligation of the left anterior descending coronary artery,followed by a 30 min reperfusion in anaesthetized rats.Incidence and severity of cardiac arrhythmias were significantly reduced by pretreatment with the EGFR kinase inhibitor AG556.Phosphorylation level of myocardial EGFR was increased during ischemia and at early reperfusion.Intramyocardial transfection of EGFR siRNA reduced EGFR mRNA and protein,and decreased the incidence of ventricular fibrillation induced by reperfusion.Interestingly,tyrosine phosphorylation levels of cardiac Na+ channel(INa) and L-type Ca2+ channel(ICa.l) were significantly increased at corresponding time points to the alteration of phosphorylated EGFR level during reperfusion.AG556 pretreatment countered the increased tyrosine phosphorylation level of Na+ and L-type Ca2+ channels induced by reperfusion.No significant alteration was observed in tyrosine phosphorylation levels of cardiac Kv4.2 and Kir2.1 channels during the cardiac ischemia/reperfusion. Conclusions These results demonstrate for the first time that EGFR plays an important role in the genesis of myocardial ischemia/reperfusion arrhythmias,which is likely mediated at least in part by enhancing tyrosine phosphorylation of cardiac Na+ and L-type Ca2+ channels.

Plasminogen activator inhibitor-1 4G/5G gene polymorphism in patients with myocardial or cerebrovascular infarction in Tianjin, China

Objective To investigate the association between the plasminogen activator inhibitor-1 (PAI-1) 4G/ 5G gene polymorphism and the occurrence of myocardial and cerebrovascular infarctions in individuals from Tianjin, China.Methods The PAI-1 genotype was determined using allele-specific polymerase chain reaction (AS-PCR) in 56 myocardial infarction (Ml) patients, 54 cerebrovascular infarction (Cl) patients and 83 unrelated healthy controls. All subjects' clinical features and plasma PAI-1 activity levels were determined.Results The PAI-1 genotype distribution frequency of the single guanine deletion/insertion 4G/5G polymorphism (located -675 bp upstream from the start of transcription) significantly differed between the patients and healthy controls. In the Ml group, the4G/4G-genotype frequency was increased, but the 4G/5G-genotype is decreased when compared to the control group. In the Cl group, both the 4G/ 4G- and 4G/5G -genotypes occured at a lower frequency than those in the control group (P<0. 001) . The plasma PAI-1 activity level in the Ml group was lowered as the presence of the 4G allele decreases. In the Cl group, the frequency of 5G/5G was much higher than that of the control group (P<0. 001). The plasma PAI-1 activity level in the Cl group was elevated as the presence of the 5G allele increased. Furthermore, positive correlation between triglyceride, glucose levels and PAI-1 activity were found in all three groups (P<0. 001).Conclusions The PAI-1 4G/5G gene polymorphism is associated with a higher risk of Ml and Cl in individuals in Tianjin, China. The deletion/insertion polymorphism is probably an important hereditary risk factor for heart diseases. Moreover, triglyceride and glucose levels of plasma have functional importance in regulating PAI-1 activity.