Diagnostic value of the novel CMR parameter “myocardial transit-time” (MyoTT) for the assessment of microvascular changes in cardiac amyloidosis and hypertrophic cardiomyopathy

Abstract

Background Coronary microvascular dysfunction (CMD) is present in various non-ischemic cardiomyopathies and in particular in those with left-ventricular hypertrophy. This study evaluated the diagnostic value of the novel cardiovascular magnetic resonance (CMR) parameter “myocardial transit-time” (MyoTT) in distinguishing cardiac amyloidosis from other hypertrophic cardiomyopathies. Methods N = 20 patients with biopsy-proven cardiac amyloidosis (CA), N = 20 patients with known hypertrophic cardiomyopathy (HCM), and N = 20 control patients without relevant cardiac disease underwent dedicated CMR studies on a 1.5-T MR scanner. The CMR protocol comprised cine and late-gadolinium-enhancement (LGE) imaging as well as first-pass perfusion acquisitions at rest for MyoTT measurement. MyoTT was defined as the blood circulation time from the orifice of the coronary arteries to the pooling in the coronary sinus (CS) reflecting the transit-time of gadolinium in the myocardial microvasculature. Results MyoTT was significantly prolonged in patients with CA compared to both groups: 14.8 ± 4.1 s in CA vs. 12.2 ± 2.5 s in HCM ( p = 0.043) vs. 7.2 ± 2.6 s in controls ( p < 0.001). Native T1 and extracellular volume (ECV) were significantly higher in CA compared to HCM and controls ( p < 0.001). Both parameters were associated with a higher diagnostic accuracy in predicting the presence of CA compared to MyoTT: area under the curve (AUC) for native T1 = 0.93 (95% confidence interval (CI) = 0.83–1.00; p < 0.001) and AUC for ECV = 0.95 (95% CI = 0.88–1.00; p < 0.001)—compared to the AUC for MyoTT = 0.76 (95% CI = 0.60–0.92; p = 0.008). In contrast, MyoTT performed better than all other CMR parameters in differentiating HCM from controls (AUC for MyoTT = 0.93; 95% CI = 0.81–1.00; p = 0.003 vs. AUC for native T1 = 0.69; 95% CI = 0.44–0.93; p = 0.20 vs. AUC for ECV = 0.85; 95% CI = 0.66–1.00; p = 0.017). Conclusion The relative severity of CMD (measured by MyoTT) in relationship to extracellular changes (measured by native T1 and/or ECV) is more pronounced in HCM compared to CA—in spite of a higher absolute MyoTT value in CA patients. Hence, MyoTT may improve our understanding of the interplay between extracellular/intracellular and intravasal changes that occur in the myocardium during the disease course of different cardiomyopathies.

Clinical and prognostic implications of capillary density in patients with cardiac light chain amyloidosis

“…Previous studies reported a high prevalence of coronary microvascular dysfunction in cardiac amyloidosis in the absence of epicardial coronary artery disease and in comparison with hypertrophic cardiomyopathy 3,14 . In this study, we directly assessed CD from cardiac tissue and comprehensively described structural and functional cardiac abnormalities associated with process of capillary rarefaction.…”

“…Previous studies reported a high prevalence of coronary microvascular dysfunction in cardiac amyloidosis in the absence of epicardial coronary artery disease and in comparison with hypertrophic cardiomyopathy. 3 , 14 In this study, we directly assessed CD from cardiac tissue and comprehensively described structural and functional cardiac abnormalities associated with process of capillary rarefaction. These findings of our study provide mechanistic insight into the pathological process of capillary rarefaction with infiltration of amyloid and underscore capillary rarefaction as a probable mechanism for diastolic dysfunction and [LV GLS] impairment in cardiac AL amyloidosis.…”

Research Progress of Imaging Methods for Detection of Microvascular Angina Pectoris in Diabetic Patients

“…Recently, in the diagnosis of microvascular diseases, Chatzantonis et al ( 66 , 67 ) introduced a new cardiovascular magnetic resonance (CMVD) parameter named “myocardial transit-time” (MyoTT), which is defined as the blood circulation time from the orfice of the coronary artery to the collection of the coronary sinus. MyoTT reflects the transmission time of gadolinium in myocardial microvascular.…”

The major factor of left ventricular systolic dysfunction in patients with cardiac amyloidosis: Amyloid overload or microcirculation impairment?

“…Heart failure with preserved ejection fraction (HFpEF) is a common manifestation of CA patients, and ultimately progress to heart failure with reduced ejection fraction (HFrEF). Chest pain symptom may present in a proportion of CA patients without significant coronary arteries stenosis (<50%) by angiography, and the microcirculation impairment of CA patients was previously reported (13)(14)(15)(16). In severe cases, it can lead to filling defect on first-pass perfusion images (17,18).…”