Cardio – MR for valvulopathy evaluation
The role of myocardial fibrosis detection in patients with tight aortic stenosis
Myocardial fibrosis in aortic stenosis is progressive. The Cardio-MR with contrast substance can identify two types of fibrosis that appear throughout the course of the disease, as follows:
- Diffuse interstitial myocardial fibrosis, is the first one, determines the expansion of the interstitial space, is reversible post-operatively and can be detected at the MRI only by T1 mapping; cannot be identified by the classic Gadolinium late capture (LGE) sequences
- Myocardial fibrosis (replacement fibrosis), occurs later in the evolution of aortic stenosis, is irreversible and can be identified in classical LGE sequences.
Replacement fibrosis may occur in the context of tight aortic stenosis, but at the same time, it may be the expression of a post-infarct scar.
Myocardial scarring (replacement fibrosis) is found in over 50% of patients with severe aortic stenosis and is associated with late mortality twice as high as in patients without scars. Once the replacement fibrosis has appeared, it is irreversible after the treatment of aortic stenosis.
Thus, evaluation by CARDIO-MR with contrast substance can identify patients with severe aortic stenosis who would benefit from an earlier aortic valve replacement intervention. Randomized studies are needed to confirm this hypothesis.
Bing R.; Cavalcante J.L.; Everett R.J.; Clavel M.-A.; Newby D.E.; Dweck M.R. Imaging and Impact of Myocardial Fibrosis in Aortic Stenosis. JACC Cardiovasc. Imaging 2019, 12, 283 LP-296. doi:10.1016/j.jcmg.2018.11.026
Evaluation of aortic regurgitation by CARDIO-MRI
Diagnosing the severity of chronic aortic regurgitation by echocardiography is often difficult, in these situations magnetic resonance is a valuable complementary method. In chronic aortic regurgitation, the MRI contributes in a significant number of cases to the reclassification of the severity of the valvulopathy or to the establishment of the severity, where the other imaging investigations are inconclusive.
This study, published in JACC Imaging, evaluated the diagnostic accuracy and prognostic utility of MRI in the assessment of aortic regurgitation. Together with NT-pro-BNP, the holodiastolic retrograde flow in the descending aorta determined by magnetic resonance was a prognostic marker in patients with chronic aortic regurgitation.
Thus, the cardio-MR evaluation is indicated in patients who have a difficult ultrasound window, or in those who, although they have an optimal ultrasound window, the ultrasound cannot accurately quantify the severity of the valvulopathy, for example in the case of eccentric jets. In order to evaluate the severity of the aortic regurgitation and to establish the morphology of the aortic valve, it is not necessary to use the contrast substance. Also without contrast administration, during the same examination, the volumes and the biventricular function are evaluated and the dimensions of the aorta can be measured at the level of all its segments. The addition of the contrast substance has the advantage that it can quantify the degree of myocardial fibrosis, with prognostic role in this population of patients.
Kammerlander AA, Wiesinger M, Duca F, Aschauer S, Binder C, Zotter Tufaro C, Nitsche C, Badre-Eslam R, Schönbauer R, Bartko P, Beitzke D, Loewe C, Hengstenberg C, Bonderman D, Mascherbauer J.
JACC Cardiovasc Imaging. 2018 Nov 8. pii: S1936-878X(18)30907-0. doi: 10.1016/j.jcmg.2018.08.036. [Epub ahead of print]
Arithmetic syndrome of mitral ring disjunction
Mitral ring disjunction represents an abnormal movement to the left atrium of mitral valve insertion. This disjunction may or may not be associated with mitral valve prolapse and increases the risk of sudden death.
116 patients with mitral ring disjunction were included in this study. 71% of these patients presented to the doctor for palpitations. Severe arrhythmic events were identified in 14 of the patients (12%). Surprisingly, the presence of mitral valve prolapse was not associated with ventricular arrhythmias.
The conclusion of the study was that ventricular arrhythmias are common in patients with mitral ring disjunction. About one quarter of patients with mitral ring disjunction do not associate mitral valve prolapse, and mitral valve prolapse is not associated with ventricular arrhythmias. Thus, mitral ring disjunction is an arrhythmogenic entity per se.
Mitral ring disjunction is difficult to visualize by echocardiography, but can be easily identified by cardio-MR.
Dejgaard L.A.; Skjølsvik E.T.; Lie Ø.H.; Ribe M.; Stokke M.K.; Hegbom F.; Scheirlynck E.S.; Gjertsen E.; Andresen K.; Helle-Valle T.M.; Hopp E.; Edvardsen T.; Haugaa K.H. The Mitral Annulus Disjunction Arrhythmic Syndrome. J. Am. Coll. Cardiol. 2018, 72, 1600 LP-1609. doi:10.1016/j.jacc.2018.07.070