Does Preliminary Chest Shape Assessment Improve the Prognostic Risk Stratification of Individuals with Mitral Annular Disjunction? A Case Report and Narrative Review

Abstract

Background: Mitral annular disjunction (MAD), a mitral annular abnormality involving the whole mitral valve annulus circumference, commonly detected in individuals with mitral valve prolapse (MVP), has been recently recognized as a potential risk factor for malignant ventricular arrhythmias (VAs) and sudden cardiac death. Recent evidence indicates that a multimodality imaging assessment comprehensive of echocardiography, cardiac magnetic resonance (CMR), and cardiac computed tomography angiography (CCTA) may improve MAD detection. To date, no previous author has considered the potential influence of chest wall conformation on MAD presence. Considering the strong association between MVP and anterior chest wall deformities and the increased prevalence of MAD among MVP individuals, we have hypothesized that MAD presence might be more frequently detected among MVP individuals with a narrow anteroposterior (A-P) thoracic diameter and/or concave-shaped chest wall conformation, as noninvasively assessed by the modified Haller index (MHI). Methods: Herein, we present a case of MVP female with relevant MAD distance and moderate mitral regurgitation (MR) who underwent a diagnostic study comprehensive of transthoracic echocardiography, transesophageal echocardiography, CMR, CCTA, and exercise stress echocardiography. Results: The patient was found with a concave-shaped chest wall conformation (MHI > 2.5) and narrow A-P thoracic diameter (<13.5 cm), with a moderate and non-hemodynamically significant MR, without areas of LGE on CMR and with low arrhythmic profile. Conclusions: A preliminary chest shape assessment by the MHI might improve the prognostic risk stratification of MVP patients with MAD, potentially identifying a benign phenotype of MVP individuals, i.e., those with a narrow A-P thoracic diameter.

Keywords: arrhythmic burden; mitral annular disjunction; mitral valve prolapse; modified Haller index; multimodality imaging assessment.

Figure 1

Modified Haller index, obtained by dividing the latero-lateral thoracic diameter by the anteroposterior thoracic diameter. (A) The latero-lateral thoracic diameter is measured by a rigid ruler coupled to a level. (B) The anteroposterior thoracic diameter is measured from the echocardiographic parasternal long-axis view as the distance between the true apex of the sector and the posterior wall of the descending aorta. The bold red line indicates the MAD distance. The bold yellow line indicates the anteroposterior thoracic diameter. Ao, aorta; LA; left atrium; LV, left ventricle; RV, right ventricle.

Figure 2

Transthoracic echocardiography. MAD assessment at end-systole from the parasternal long-axis view (A), from the apical four-chamber view (B), and from the apical two-chamber view (C). The bold red line indicates the MAD distance. Ao, aorta; LA; left atrium; LV, left ventricle; RA, right atrium; RV, right ventricle.

Figure 3

Bull’s-eye plot illustrating the regional longitudinal strain at basal, mid, and apical levels along with LV-GLS magnitude. LV-GLS was moderately impaired, particularly at basal and mid-level, with apical sparing. LV-GLS left ventricular-global longitudinal strain.

Figure 4

Transesophageal echocardiography. MAD assessment at end-systole from the mid-esophageal three-chamber view (A), four-chamber view (B), and two-chamber view (C). The bold red line indicates the MAD distance. Ao, aorta; LA; left atrium; LV, left ventricle; RA, right atrium; RV, right ventricle. (A) is reproduced from the ref. [4].

Figure 5

Cardiac magnetic resonance. MAD assessment at end-systole from the three-chamber view (A), four-chamber view (B), and two-chamber view (C). The bold red line indicates the MAD distance. Ao, aorta; LA; left atrium; LV, left ventricle; RA, right atrium; RV, right ventricle. (A) is reproduced from the ref. [4].

Figure 6

Cardiac computed tomography angiography. MAD assessment at end-systole from the multiplanar reconstructed three-chamber view (A), four-chamber view (B), and two-chamber view (C). The bold red line indicates the MAD distance. Ao, aorta; LA; left atrium; LV, left ventricle. (A) is reproduced from the ref. [4].

Figure 7

Moderate mitral regurgitation detected on resting transthoracic echocardiography from the parasternal long-axis view (A), on transesophageal echocardiography from the bicommissural view (B), and on exercise stress echocardiography from the apical four-chamber view recorded at peak exercise (C). Ao, aorta; LA; left atrium; LV left ventricle; RA, right atrium; RV, right ventricle.

Figure 8

12-lead ECG obtained at peak exercise during exercise stress echocardiography. ECG, electrocardiogram.