Characteristic Histopathological Findings and Cardiac Arrest Rhythm in Isolated Mitral Valve Prolapse and Sudden Cardiac Death

Abstract

Background The association between mitral valve prolapse (MVP) and sudden death remains controversial. We aimed to describe histopathological changes in individuals with autopsy-determined isolated MVP (iMVP) and sudden death and document cardiac arrest rhythm. Methods and Results The Australian National Coronial Information System database was used to identify cases of iMVP between 2000 and 2018. Histopathological changes in iMVP and sudden death were compared with 2 control cohorts matched for age, sex, height, and weight (1 group with noncardiac death and 1 group with cardiac death). Data linkage with ambulance services provided cardiac arrest rhythm for iMVP cases. From 77 221 cardiovascular deaths in the National Coronial Information System database, there were 376 cases with MVP. Individual case review yielded 71 cases of iMVP. Mean age was 49±18 years, and 51% were women. Individuals with iMVP had higher cardiac mass (447 g versus 355 g; P<0.001) compared with noncardiac death, but similar cardiac mass (447 g versus 438 g; P=0.64) compared with cardiac death. Individuals with iMVP had larger mitral valve annulus compared with noncardiac death (121 versus 108 mm; P<0.001) and cardiac death (121 versus 110 mm; P=0.002), and more left ventricular fibrosis (79% versus 38%; P<0.001) compared with noncardiac death controls. In those with iMVP and witnessed cardiac arrest, 94% had ventricular fibrillation. Conclusions Individuals with iMVP and sudden death have increased cardiac mass, mitral annulus size, and left ventricular fibrosis compared with a matched cohort, with cardiac arrest caused by ventricular fibrillation. The histopathological changes in iMVP may provide the substrate necessary for development of malignant ventricular arrhythmias.

Keywords: sudden death; valvular heart disease; ventricular arrhythmia.

Figure 1

Case identification. *Other significant findings include: ischemic heart disease (36), previous cardiac surgery (8), histological myocarditis (4), significant left ventricular hypertrophy (3), dilated cardiomyopathy (2), severe mitral regurgitation (1), arrhythmogenic right ventricular cardiomyopathy (1), bicuspid aortic valve with aortic coarctation (1), infection (7), respiratory (6), drug overdose (3), cirrhosis (3), head injury (3), metastatic carcinoma (1), hyponatremia (1), and suicide (1). AMI indicates acute myocardial infarction; MVA, motor vehicle accident; and MVP, mitral valve prolapse.

Figure 2

Initial cardiac rhythm in cases of autopsy‐determined isolated mitral valve prolapse (iMVP). VF indicates ventricular fibrillation.

Figure 3

Histological analysis with initial cardiac rhythm for representative cases of isolated mitral valve prolapse (iMVP) and sudden cardiac death. A, A 31‐year‐old woman with witnessed cardiac arrest while resting in bed and ventricular fibrillation (VF). Histopathological examination showed myxomatous change in both mitral valve leaflets with focal left ventricular fibrosis in a subendocardial‐midmural distribution and papillary muscle fibrosis. B, A 45‐year‐old woman found on the toilet with VF after an unwitnessed cardiac arrest. Histopathological examination showed thickening and billowing of both mitral valve leaflets with multisegment left ventricular fibrosis in a subendocardial‐midmural distribution. C, A 34‐year‐old woman found collapsed in the bathroom with asystole after an unwitnessed cardiac arrest. Histopathological examination showed myxomatous change in both mitral valve leaflets with multisegment left ventricular fibrosis in a midmural distribution. D, A 25‐year‐old woman with witnessed cardiac arrest while washing dishes and VF. Histopathological examination showed myxomatous change in both mitral valve leaflets with multisegment left ventricular fibrosis in a subendocardial‐midmural distribution. E, A 47‐year‐old woman found collapsed in the bathroom with VF after an unwitnessed cardiac arrest. Histopathological examination showed thickened and floppy mitral valve leaflets with no evidence of left ventricular fibrosis.