lf l could also throw my conjecture here, l think it may be mitral regurgitation as it would be mechanical, if left untreated could cause atrial fibrilation which explains the 'fluttering' he experiences, it would allow one to be on disability, one could need open-heart surgery to fix it (though a transcatheter mitral valve repair is a more common procedure), but it's not that strongly associated with genetics as the cardiomyopathy you mentioned, not does it fit with his age range... so, l wouldn't really bet on this.