CMR-based T1-mapping offers superior diagnostic value compared to longitudinal strain-based assessment of relative apical sparing in cardiac amyloidosis.

Cardiac amyloidosis (CA) is an infiltrative disease. In the present study, we compared the diagnostic accuracy of cardiovascular magnetic resonance (CMR)-based T1-mapping and subsequent extracellular volume fraction (ECV) measurement and longitudinal strain analysis in the same patients with (a) biopsy-proven cardiac amyloidosis (CA) and (b) hypertrophic cardiomyopathy (HCM). N = 30 patients with CA, N = 20 patients with HCM and N = 15 healthy control patients without relevant cardiac disease underwent dedicated CMR studies. The CMR protocol included standard sequences for cine-imaging, native and post-contrast T1-mapping and late-gadolinium-enhancement. ECV measurements were based on pre- and post-contrast T1-mapping images. Feature-tracking analysis was used to calculate 3D left ventricular longitudinal strain (LV-LS) in basal, mid and apical short-axis cine-images and to assess the presence of relative apical sparing. Receiver-operating-characteristic analysis revealed an area-under-the-curve regarding the differentiation of CA from HCM of 0.984 for native T1-mapping (p < 0.001), of 0.985 for ECV (p < 0.001) and only 0.740 for the "apical-to-(basal + midventricular)"-ratio of LV-LS (p = 0.012). A multivariable logistical regression analysis showed that ECV was the only statistically significant predictor of CA when compared to the parameter LV-LS or to the parameter "apical-to-(basal + midventricular)" LV-RLS-ratio. Native T1-mapping and ECV measurement are both superior to longitudinal strain measurement (with assessment of relative apical sparing) regarding the appropriate diagnosis of CA.

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

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.

Diagnostic value of global myocardial perfusion reserve assessment based on coronary sinus flow measurements using cardiovascular magnetic resonance in addition to myocardial stress perfusion imaging.

AIMS: Myocardial perfusion reserve (MPR) is defined as the maximal possible increase in myocardial blood flow (MBF) above baseline conditions. Global MBF can be measured non-invasively by means of coronary sinus flow velocity encoded cine (VENC) cardiovascular magnetic resonance (CMR). We aimed to explore the relationship between global MBF/MPR and the extent and severity of coronary artery disease (CAD) in patients referred for CAD work-up by adenosine-stress CMR. METHODS AND RESULTS: Fifty-eight patients with suspected obstructive CAD underwent both adenosine-stress CMR and invasive coronary angiography. In addition to standard cine- and late gadolinium enhancement (LGE)-imaging, first-pass myocardial perfusion imaging (MPI) and coronary sinus flow measurements (VENC) were performed at rest and during peak stress (after 140 µg/kg/min adenosine), respectively. Nineteen young patients with a very low CAD pre-test probability and normal adenosine-stress CMR formed the control group. Fifty-nine percent (n = 34) of the study group showed segmental, adenosine-induced myocardial perfusion defects compared to none of the control group (P < 0.001). Global MPR was lower in the study group compared to the control group: 2.3 (1.5-3.1) vs. 3.1 (2.0-4.3), P = 0.016. The SYNTAX score was higher in the study group patients with an impaired MPR (<2) compared to those with a preserved MPR (3.0 vs. 16.0, P = 0.01)-mainly due to higher prevalence of proximal epicardial stenoses (60% vs. 27%, P = 0.02) and multi-vessel disease (56% vs. 24%, P = 0.017). The diagnostic yield of stress CMR for the diagnosis of CAD (>50% stenosis) increased from 65to 88% when global MPR assessment was considered in addition to MPI (P = 0.025). CONCLUSIONS: Global MBF and MPR values correlate with the anatomical extent and complexity of CAD and increase the diagnostic yield of non-invasive stress CMR in the work-up of CAD. CMR-based MBF and MPR measurements may play a future role in the evaluation of the total ischaemic burden-particularly in patients with multi-vessel disease.