Unrecognized Cardiac Amyloidosis at the Time of Mitral Valve Surgery: Incidence and Outcomes

Objective: It is increasingly recognized that cardiac amyloidosis can occur in patients with severe aortic stenosis undergoing both surgical and transcatheter valve replacements. We aimed to investigate whether unrecognized cardiac amyloidosis may also occur in patients with severe mitral valve disease undergoing surgery. Methods: The pathology department database at our center was retrospectively analyzed over a 10-year period for cases in which the mitral valve or another type of cardiac tissue removed at the time of mitral surgery demonstrated incidental amyloidosis. Clinical and echocardiographic variables were collected from the electronic medical record and the echocardiographic database. Results: Between 2007 and 2016, a total of 7,733 mitral valve surgical specimens were received. Of these, there were 15 cases in which the mitral valve, or another type of cardiac tissue removed at surgery, demonstrated incidentally detected amyloidosis. The most frequent comorbidities were hypertension (87%) and atrial fibrillation (80%); 13 patients (87%) underwent bioprosthetic mitral valve replacement, and 2 patients (13%) underwent mitral valve repair. Sites of amyloid deposition were the mitral valve (80%), left atrial appendage (33%), and subaortic tissue (7%); 14 patients (93%) had wild-type transthyretin amyloid. The mean duration of follow-up was 1,023 days (range: 29-2,811 days). There were no surgical complications in the follow-up period. Conclusions: Over a 10-year period, incidentally detected cardiac amyloidosis occurred in 0.2% of the mitral valve surgical cases. The outcomes for these patients undergoing mitral valve surgery were excellent, with no complications or deaths attributable to surgery at a mean follow-up of 1,023 days.