The decision to refer or accept a patient for mitral valve surgery is substantially different than for most other cardiac surgical operations. Unlike other structural cardiac diseases, completely asymptomatic patients at very low risk of sudden death are often considered for surgery in the setting of severe regurgitation. Secondly, the operation performed for degenerative mitral regurgitation is surgeon “skill and experience” dependent, which is very different than most other operations for structural heart disease (e.g. essentially all patients with calcific aortic stenosis referred to surgery undergo aortic valve replacement regardless of surgeon “skill and experience”.)
It is interesting to note that longitudinal studies of the natural history of mitral valve prolapse have not taken into account the underlying etiology - Barlow's disease or fibroelastic deficiency. On the basis of natural history, typical lesions, and typical regurgitation patterns, one can, however, make the assumption that patients with Barlow's disease are more likely to undergo a longer period of event-free survival before developing typically accepted indications for surgery, such as symptoms, depressed left ventricular function, moderate pulmonary hypertension, or atrial fibrillation. Fibroelastic deficiency, on the other hand, often presents with holo-systolic regurgitation, in older individuals, and may require closer follow-up in anticipation of a shorter event-free period prior to surgical referral.
This logic is highlighted in two recent articles assessing event-free survival in asymptomatic patients with severe mitral regurgitation. Enriquez-Sarano and colleagues1 reported on a cohort of patients with quantitatively graded severe mitral regurgitation with a mean age of 63 years (typical of fibroelastic deficiency), and concluded that early referral should be considered because of high event rates, including increased cardiac mortality, over 5 years of follow-up. In contrast, Rosenhek and colleagues2 presented good results with a policy of watchful waiting in patients with semi-quantitatively graded severe mitral regurgitation with a mean age of 55 years, which is more typical of Barlow's disease (although by 8 years of follow-up many patients developed an indication for surgery, also typical of Barlow's disease). Interestingly, when Rosenhek et al.2 looked at the subgroup with flail leaflets (i.e. ruptured chordae), the event-free survival rate diminished, although the numbers were too small to make any significant conclusions. Nonetheless, until future reports take into account specific lesions and presumed etiology in terms of the impact on the natural history, it is logical to counsel asymptomatic patients with Barlow's disease and chordal elongation (mid-systolic regurgitation) that continued close follow-up is a reasonable alternative to early surgery, emphasizing most will require elective valve reconstruction within several years of follow-up. On the other hand, patients with fibroelastic deficiency and severe regurgitation should be made aware that events are common early during follow-up so early surgery is advisable.
Portions excerpted, with permission, Adams DH, Anyanwu AC. The cardiologist's role in increasing the rate of mitral valve repair in degenerative disease. Current Opinion in Cardiology 2008, 23:105-110.
- 1. Enriquez-Sarano M, Avierinos JF, Messika-Zeitoun D, et al. Quantitative determinants of the outcome of asymptomatic mitral regurgitation. N Engl J Med 2005; 352:875-883.
- 2. Rosenhek R, Rader F, Klaar U, et al. Outcome of watchful waiting in asymptomatic severe mitral regurgitation. Circulation 2006; 113:2238-2244.