T-wave and its association with myocardial fibrosis on cardiovascular magnetic resonance examination

Background

Risk stratification in non-ischemic myocardial disease poses a challenge. While cardiovascular magnetic resonance (CMR) is a comprehensive tool, the electrocardiogram (ECG) provides quick impactful clinical information. Studying the relationships between CMR and ECG can provide much-needed risk stratification. We evaluated the electrocardiographic signature of myocardial fibrosis defined as presence of late gadolinium enhancement (LGE) or extracellular volume fraction (ECV) ≥29%.

Methods

We evaluated 240 consecutive patients (51% female, 47.1 ± 16.6 years) referred for a clinical CMR who underwent 12-lead ECGs within 90 days. ECG parameters studied to determine association with myocardial fibrosis included heart rate, QRS amplitude/duration, T-wave amplitude, corrected QT and QT peak, and Tpeak-Tend. Abnormal T-wave was defined as low T-wave amplitude ≤200 µV or a negative T wave, both in leads II and V5.

Results

Of the 147 (61.3%) patients with myocardial fibrosis, 67 (28.2%) had ECV ≥ 29%, and 132 (54.6%) had non-ischemic LGE. An abnormal T-wave was more prevalent in patients with versus without myocardial fibrosis (66% versus 42%, p < .001). Multivariable analysis demonstrated that abnormal T-wave (OR 1.95, 95% CI 1.09–3.49, p = .03) was associated with myocardial fibrosis (ECV ≥ 29% or LGE) after adjustment for clinical covariates (age, gender, history of hypertension, and heart failure). Dynamic nomogram for predicting myocardial fibrosis using clinical parameters and the T-wave was developed: https://normogram.shinyapps.io/CMR_Fibrosis/ .

Conclusion

Low T-wave amplitude ≤ 200 µV or negative T-waves are independently associated with myocardial fibrosis. Prospective evaluation of T-wave amplitude may identify patients with a high probability of myocardial fibrosis and guide further indication for CMR.

     

Cardiac magnetic resonance in myocardial disease

For a number of patients it is difficult to diagnose the cause of cardiac disease. In such patients cardiac magnetic resonance is useful for helping to make a differential diagnosis between ischaemic and dilated cardiomyopathy; identifying patients with myocarditis; diagnosing cardiac involvement in sarcoidosis and Chagas' disease; identifying patients with unusual forms of hypertrophic cardiomyopathy and those with continuing myocardial damage; and defining the sequelae of ablation treatment for hypertrophic obstructive cardiomyopathy.     

Assessment of myocardial viability by cardiovascular magnetic resonance

Patients with ischemic heart disease may have left ventricular (LV) dysfunction due to reversible or irreversible causes. The ability to distinguish viable myocardium with dysfunction due to a reversible etiology (hibernation, stunning) from nonviable scar is critical for determining proper management of the patient. Cardiovascular magnetic resonance (CMR) is a technique that has been established to be useful for the detection of myocardial viability and advancements in the field promise to further increase its utility. In this review we describe the features of CMR that make it suited for this purpose and outline promising developments that may soon make CMR the reference standard for viability assessment.     

心脏磁共振诊断非缺血性心肌纤维化中的应用进展

心脏磁共振使非缺血性心肌纤维化的无创诊断和预后评价成为了可能。目前的半定量延迟强化显像,影响因素较多,在弥漫性心肌纤维化中很难形成对比,得到可靠信息。T1mapping是一种新型的可定量评估心肌特征的方法,对局部及弥漫性心肌病变,心肌细胞外间质扩大及水肿方面有着良好的应用前景,助于对弥漫性病变进行早期诊断和治疗。     

磁共振延迟增强显像诊断心肌梗死的临床研究

目的 了解磁共振延迟增强(MR-DE)显像在心肌梗死诊断中的临床意义。方法 42例拟诊冠心病的患者,按临床分为心肌梗死、心肌缺血、正常3组,行MR-DE显像,其中25例行冠状动脉造影(CAG),并按冠脉狭窄程度分为狭窄<50％,50％～99％和100％3组。计算MR-DE检出心肌梗死的敏感性与特异性,并分别分析临床分组和CAG分组的MR-DE结果。结果 利用延迟增强判断心肌梗死,敏感性、特异性和诊断准确性分别为87.5％,94.1％和92.8％。出现延迟增强的比例,在临床分组中,分别为87.5％,8.7％和0％;在CAG分组中,分別为0％,50％和100％。结论 MR-DE显像对心肌梗死诊断有较高临床意义。     

Assessment of myocardial ischemia with cardiovascular magnetic resonance

Assessment of myocardial ischemia in symptomatic patients remains a common and challenging clinical situation faced by physicians. Risk stratification by presence of ischemia provides important utility for both prognostic assessment and management. Unfortunately, current noninvasive modalities possess numerous limitations and have limited prognostic capacity. More recently, ischemia assessment by cardiovascular magnetic resonance (CMR) has been shown to be a safe, available, and potentially cost-effective alternative with both high diagnostic and prognostic accuracy. Cardiovascular magnetic resonance has numerous advantages over other noninvasive methods, including high temporal and spatial resolution, relatively few contraindications, and absence of ionizing radiation. Furthermore, studies assessing the clinical utility and cost effectiveness of CMR in the short-term setting for patients without evidence of an acute myocardial infarction have also demonstrated favorable results. This review will cover techniques of ischemia assessment with CMR by both stress-induced wall motion abnormalities as well as myocardial perfusion imaging. The diagnostic and prognostic performance studies will also be reviewed, and the use of CMR for ischemia assessment will be compared with other commonly used noninvasive modalities.     

Gender-specific differences in left ventricular remodelling and fibrosis in hypertrophic cardiomyopathy: insights from cardiovascular magnetic resonance

BACKGROUND: Gender is an independent risk factor for heart failure mortality in hypertrophic cardiomyopathy (HCM). AIMS: To explore the interaction between gender, myocardial fibrosis and remodelling in HCM. METHODS: We studied 64 HCM patients (28 females, aged 51+/-16 years) categorized as non-obstructive (HNCM, n=31) or obstructive (HOCM, n=33) and 60 healthy subjects (31 females, aged 43+/-14 years). Cine imaging was performed to assess left ventricular volumes and mass. LV remodelling index (LVRI) was calculated. Extension of late gadolinium enhancement (LGE) was quantified. RESULTS: Females in the control group and in the HNCM group had a lower LVRI than males (control: 0.7+/-0.1 vs. 0.9+/-0.2 g/ml, p<0.002; HNCM: 1.1+/-0.2 vs. 1.5+/-0.5 g/ml, p<0.001). In contrast, HOCM females had a similar LVRI compared to males (1.8+/-0.5 vs. 1.7+/-0.4 g/ml, p=ns). Thus the increase in LVRI was more pronounced in females compared to males. LGE was noted in 70% of the patients. No relation was found between the presence or the quantity of myocardial fibrosis and gender in any of the patient subgroups. CONCLUSION: Our data suggest a disproportionate degree of remodelling in different forms of HCM depending on gender. Gender does not appear to influence the quantity of fibrosis as defined by LGE.     

Assessment of liver fibrosis using T1 mapping on Gd-EOB-DTPA-enhanced magnetic resonance

BackgroundFew studies have investigated the value of Gd-EOB-DTPA-enhanced T1 mapping in exact fibrosis staging, especially its correlation with hepatic molecular transporters.AimsTo investigate the diagnostic value of Gd-EOB-DTPA-enhanced T1 mapping in staging liver fibrosis and its relationship with hepatic molecular transporters.MethodsThirty rats were divided into the carbon tetrachloride-induced fibrosis groups and a control group. T1-mapping was performed before and 20 min after administration of Gd-EOB-DTPA. The T1 relaxation time and reduction rate (Δ%) were calculated, and their correlations with the degree of fibrosis, necroinflammatory activity, iron load and hepatic molecular transporters were assessed and compared.ResultsHepatobiliary phase T1 relaxation time (HBP) and Δ% were different between each adjacent fibrosis subgroups(P = 0.000–0.042). Very strong correlations existed between fibrosis and both HBP and Δ% (r = 0.960/−0.952), and multivariate analyses revealed that fibrosis was the only factor independently predicted by HBP (P = 0.000) and Δ% (P = 0.001), comparing to necroinflammatory activity and iron load. The expression of the organic anion transporting polypeptide1a1 (Oatp1a1) was significantly correlated with HBP and Δ% at both mRNA (r = −0.741/0.697) and protein (r = −0.577/0.602) levels. Weaker correlations were found for multidrug resistance associated protein2 (Mrp2). Generally, both transporters showed decreasing levels with increasing degrees of fibrosis.ConclusionGd-EOB-DTPA-enhanced T1 mapping may provide a reliable diagnostic tool in staging liver fibrosis, and can be regarded as a useful imaging biomarker of hepatocyte transporter function.     

Quantification of myocardial iron overload by cardiovascular magnetic resonance imaging T2* and review of the literature

Heart failure due to myocardial iron overload remains the leading cause of death in patients with transfusion-dependent anemias. Iron overload-induced cardiomyopathy is reversible if intensive chelation therapy is instituted on time. Thus, early detection of myocardial iron deposition is imperative to prevent overt heart failure. Conventional cardiac monitoring, including physical examination, electrocardiography, echocardiography or serum ferritin levels fail to predict manifest or subclinical myocardial involvement resulting from iron overload. Cardiovascular magnetic resonance imaging T2* (cMRI-T2*, pronounced T2 star) times correlate well with myocardial iron levels. This timely review focuses on the utility of cMRI-T2*, for the preclinical detection of myocardial iron overload and monitoring of myocardial iron content during chelation therapy.