Mitral Annular Disjunction: Review of an Increasingly Recognized Mitral Valve Entity

Abstract

Mitral annular disjunction (MAD) refers to atrial displacement of the hinge point of the mitral valve annulus from the ventricular myocardium. MAD leads to paradoxical expansion of the annulus in systole and may often be associated with mitral valve prolapse (MVP), leaflet degeneration, myocardial and papillary muscle fibrosis, and, potentially, malignant cardiac arrhythmias. Patients with MAD and MVP may present similarly, and MAD is potentially the missing link in explaining why some patients with MVP experience adverse outcomes. Patients with a 5 mm or longer MAD distance have an elevated risk of malignant cardiac arrhythmia compared with those with a shorter MAD distance. Evaluation for MAD is an important component of cardiac imaging, especially in patients with MVP and unexplained cardiac arrhythmias. Cardiac MRI is an important diagnostic tool that aids in recognizing and quantifying MAD, MVP, and fibrosis in the papillary muscle and myocardium, which may predict and help improve outcomes following electrophysiology procedures and mitral valve surgery. This article reviews the history, pathophysiology, controversy, prevalence, clinical implications, and imaging considerations of MAD, focusing on cardiac MRI. Keywords: MR-Dynamic Contrast Enhanced, Cardiac, Mitral Valve, Mitral Annular Disjunction, Mitral Valve Prolapse, Floppy Mitral Valve, Cardiac MRI, Arrhythmia, Sudden Cardiac Death, Barlow Valve © RSNA, 2023.

Keywords: Arrhythmia; Barlow Valve; Cardiac; Cardiac MRI; Floppy Mitral Valve; MR–Dynamic Contrast Enhanced; Mitral Annular Disjunction; Mitral Valve; Mitral Valve Prolapse; Sudden Cardiac Death.

Figure 1:

(A) A schematic of the normal mitral valve apparatus with annulus, leaflets, chordae tendineae, and papillary muscles. A1–A3: anterior, middle, and medial scallops of the anterior valve leaflet. P1–P3: superolateral, middle, and inferoseptal scallops of the posterior mitral valve leaflet (A = anterior, L = lateral, M = medial). (B) Two-chamber and (C) four-chamber CT images of the mitral valve leaflet insertion to the top of the left ventricular myocardium denote the normal anatomy of the mitral annulus (arrows in B and C).

Figure 2:

Images in a 73-year-old male patient who presented with chest pain and underwent workup for acute coronary syndrome. Cardiac CT angiograms show incidental mitral valve prolapse with thickening and prolapse of the mitral valve leaflets (black arrow) and 7-mm disjunction of the posterior mitral annulus (white arrowhead), as shown on the end-systolic (A) two-chamber and (B) four-chamber view images.

Figure 3:

Images in a 24-year-old asymptomatic female patient with mitral valve prolapse diagnosed at 3 years of age. (A) Her electrocardiogram showed normal sinus rhythm. A three-chamber view at echocardiography showed a 10-mm gap between the mitral valve hinge point and left ventricular myocardium (black arrow). On the (B) two-chamber and (C) three-chamber views of cine steady-state free precession cardiac MRI, this gap was confirmed in the end-systolic phase and measured 6 mm (black arrow).

Figure 4:

Images in a 43-year-old female patient with mitral valve prolapse who presented with supraventricular tachycardia. Three-chamber (A) end-diastolic and (B) end-systolic and (C) two-chamber end-systolic views from cine steady-state free precession cardiac MRI demonstrate mitral annular disjunction with a distance of 6 mm (white arrowhead). The mitral valve leaflets were thickened and redundant with 15-mm prolapse (white arrow) of the posterior leaflet.

Figure 5:

Images in a 40-year-old male patient with near-syncopal episodes, normal sinus rhythm, and T wave inversions at resting electrocardiography. Transthoracic echocardiography showed normal left ventricular function and stable (for 6 years) moderate mitral incompetence, prolapse, and myxomatous valve leaflets. Outpatient Holter monitoring demonstrated infrequent atrial and ventricular ectopy. End-systolic (A) two-chamber and (B) four-chamber cine steady-state free precession cardiac MRI views helped confirm echocardiography findings of bileaflet prolapse (white arrow) (7 to 10 mm). The images also showed a 7-mm mitral annular disjunction with paradoxical outward curling of the annulus (white arrowhead). (C) There was minimal midmyocardial focal late gadolinium enhancement in the inferolateral basal left ventricle, as observed on the short-axis image (black arrow).

Figure 6:

Schematic illustration of the atrioventricular junction during LV systole. (A) The leaflet hinge point in the normal position at the top of the basal LV (black arrow). (B) Mitral annular disjunction (MAD) with a displaced hinge point to the LA away from the normal position. (C) Magnified view of MAD with a caliper measuring MAD distance (black arrow). (D) Mitral valve prolapse (MVP) with bileaflet prolapse. (E) Magnified view of MVP with measurement of the anterior leaflet (white arrow) and posterior leaflet (white arrowhead) from the basal mitral annulus plane (depicted by a black line connecting the anterior and posterior leaflet). D and E also illustrate a folded posterior mitral leaflet along the LA wall mimicking the displaced hinge point, also known as pseudo-MAD (black arrowhead). Ao = aorta, LA = left atrium, LV = left ventricle.

Figure 7:

Pickelhaube sign at tissue Doppler imaging. A high-velocity midsystolic spike of the mitral valve annulus (more than 16 cm/sec) resembles a German military helmet with a spike (arrow).

Figure 8:

Images in a 55-year-old female patient with frequent episodes of presyncope and syncope diagnosed with systolic dysfunction, high premature ventricular complex (PVC) burden after ablation (20%), nonsustained ventricular tachycardia, and mitral regurgitation. (A) As measured on the three-chamber view cardiac MR image, there was mitral valve prolapse (white arrow) and 8 mm of mitral annular disjunction (white arrowhead). (B) Precontrast T1 map demonstrates increased native T1 values in the basal inferior (1130 msec) and lateral (1176 msec) walls. (C-E) There was extensive delayed gadolinium enhancement in the basal inferolateral and lateral walls and the papillary muscle (black arrows) on delayed postcontrast images. This was partially from prior PVC ablation but may also be due to underlying fibrosis.

Figure 9:

Images in a 60-year-old male patient with long-standing mitral regurgitation, bileaflet prolapse, and low normal left ventricular ejection fraction who recently developed symptomatic palpitations with 10% premature ventricular complex (PVC) burden and frequent bigeminy. (A) Three-chamber cine steady-state free precession cardiac MRI view demonstrates 6–8-mm bileaflet prolapse (black arrow) with 9-mm mitral annular disjunction (white arrowhead). (B) The T1 map at the basal section demonstrates diffuse high T1 values ranging between 1103 msec and 1252 msec. (C, D) Short-axis postcontrast cardiac MRI views demonstrate basal midmyocardial (black arrows in C) and papillary muscle (black arrow in D) late gadolinium enhancement. At electrophysiologic-guided endocardial mapping during ablation of frequent PVC, there was abnormal voltage mapping throughout the basal LV. PVC localized to the basal inferolateral wall and posterior papillary muscle as shown on (E, F) voltage maps and (G) electroanatomic images. LV = left ventricle, RFA = radiofrequency ablation.

Figure 10:

Flowchart shows the approach for recognizing MAD correlated with elevated risk of cardiac arrhythmia. LV = left ventricle, −ve = negative, +ve = positive, 3C = three-chamber.