LETTERS TO THE EDITOR Flail Mitral Valve and Sudden Cardiac Death

The recent report by Grigioni et al. (1) of an increased risk of sudden death in mitral regurgitation due to a flail leaflet was of interest to us, and we are sure, to many other cardiologists. Certainly, the Mayo Clinic group has been instrumental in advancing our understanding of the natural history of patients with mitral regurgitation. Specifically, Grigioni et al. (1) presented data suggesting that patients with a flail mitral leaflet, even in the absence of severe symptoms and left ventricular dysfunction, incur an enhanced risk of sudden unexpected death due to their valvular abnormality. As suggested in the accompanying editorial by Carabello (2), the potentially important role of associated atherosclerotic coronary disease in causing these sudden deaths could not be excluded, particularly given the rather advanced ages of those patients who died (mean age 71 years). Of the 25 sudden deaths, coronary artery disease was excluded in only four, and seven other patients were said to have a history consistent with this condition. We wonder: if such patients, who are likely to have ischemic heart disease (an alternative cause for sudden death at an advanced age), had been segregated in the authors’ sophisticated statistical analysis, would their results and conclusions have been as definitive? Perhaps under these circumstances, the authors should have been more conservative in their conclusions: “Sudden death is relatively common in patients with mitral regurgitation–flail leaflet who are conservatively managed,” as well as in the attractive title of the paper: “Sudden Death in Mitral Regurgitation Due to Flail Leaflet,” rather than potentially over-estimating the consequences of the flail mitral valve to clinicians. A second area of concern involves issues related to mitral valve anatomy. Although we assume that the etiology of the flail leaflets and mitral regurgitation in most of the patients of Grigioni et al. (1) is mitral valve prolapse (i.e., myxomatous degeneration) with chordal disruption, this is not explicitly stated. Flail leaflets demonstrate a broad morphologic and functional spectrum, and there appears to be some uncertainty as to whether relatively mild or moderate degrees of flail (due to localized chordal disruption) were included among the authors’ study group of 348 patients, who have been characterized in the report as being at increased risk for sudden death. Should patients with relatively mild or segmental flail leaflets also be regarded to be at increased risk? Are the authors suggesting that all patients with flail segments represent a distinct subgroup within the mitral valve prolapse spectrum, as apposed to other patients with prolapse with moderate to severe mitral regurgitation, such as those with elongated chordae? Perhaps a clarification of these points would help clinicians better appreciate the potential consequences of the flail mitral valve.