Summary
Background
While occasional reports of mitral valve chordal rupture have been described in hypertrophic cardiomyopathy, the exact prevalence and characteristics of this event in a large medical cohort have not been reported.
Aim
To assess the prevalence of mitral valve chordal rupture in hypertrophic cardiomyopathy and the clinical, echocardiographic, surgical and histological profiles of those patients.
Methods
We searched for patients with mitral valve chordal rupture diagnosed by echocardiography among all electronic files of patients admitted to our centre for hypertrophic cardiomyopathy between 2000 and 2010.
Results
Among 580 patients admitted for hypertrophic cardiomyopathy, six patients (1%, 5 men, age 68–71 years) presented with mitral valve chordal rupture, symptomatic in five cases, always involving the posterior mitral leaflet. In all cases, echocardiography before rupture showed mitral valve systolic anterior motion, with anterior (and not posterior) leaflet elongation compared with a random sample of patients with non-obstructive hypertrophic cardiomyopathy ( P = 0.006) (and similar to that observed in obstructive hypertrophic cardiomyopathy). Significant resting left ventricular outflow tract obstruction was always present before rupture and disappeared after rupture in the five cases requiring mitral valve surgery for severe mitral regurgitation. Histological findings were consistent with extensive myxomatous degeneration in all cases.
Conclusion
Mitral valve chordal rupture is: infrequent in hypertrophic cardiomyopathy; occurs in aged patients with obstructive disease; involves, essentially, the posterior mitral leaflet; and causes, in general, severe mitral regurgitation requiring surgery. Myxomatous degeneration may be the substrate for rupture in these patients.
Résumé
Contexte
Bien que des cas isolés de rupture de cordages de la valve mitrale aient été rapportés dans la cardiomyopathie hypertrophique, les caractéristiques de cet événement n’ont jamais été décrites dans une large cohorte médicale.
Objectif
Déterminer la prévalence et les profils clinique, échographique, opératoire et histologique des patients présentant une rupture de cordages de la valve mitrale dans la cardiomyopathie hypertrophique.
Méthodes
Nous avons colligé les ruptures de cordages de la valve mitrale parmi les patients hospitalisés pour cardiomyopathie hypertrophique dans notre centre entre 2000 et 2010.
Résultats
Parmi 580 patients, six (1 %, cinq hommes, de 68 à 71 ans) présentaient une rupture de cordages de la valve mitrale, symptomatique dans cinq cas, impliquant toujours le feuillet postérieur. L’échographie avant rupture retrouvait constamment un mouvement systolique antérieur de la valve mitrale avec élongation du feuillet antérieur par rapport à un échantillon de patients avec cardiomyopathie hypertrophique non obstructive ( p = 0,006) (et similaire à celle observée en cas de cardiomyopathie hypertrophique obstructive). Une obstruction sous-aortique de repos était constamment retrouvée avant rupture et disparaissait après dans les cinq cas nécessitant une chirurgie mitrale pour fuite importante. L’histologie retrouvait une dégénérescence myxoïde extensive dans tous les cas.
Conclusion
La rupture de cordages de la valve mitrale est : rare dans la cardiomyopathie hypertrophique ; survient chez les patients âgés avec forme obstructive ; touche le feuillet postérieur ; et entraîne en général une fuite mitrale sévère nécessitant un traitement chirurgical. Une dégénérescence myxoïde pourrait constituer le substrat de la rupture chez ces patients.
Background
Hypertrophic cardiomyopathy (HCM) is the most common monogenic cardiac disease, affecting approximately 1 in 500 individuals . HCM usually involves the mitral valve (MV), with intrinsic abnormalities, such as leaflet thickening and/or elongation, anomalous mitral papillary muscles or chordae, direct papillary muscle insertion onto the mitral leaflet, chordal rupture and MV prolapse . Excessive leaflet tissue, anterior displacement of the MV apparatus and chordal abnormalities also play a primary role in the systolic anterior motion (SAM) of the MV and left ventricular outflow tract (LVOT) obstruction . Mitral regurgitation (MR) in HCM is either caused by valve distortion as a consequence of SAM and/or is secondary to MV structural abnormalities.
While one surgical series of five patients has been published previously , and isolated cases have been reported , the exact prevalence and characteristics of MV chordal rupture (MVCR), which often leads to severe MR requiring surgery, have not been reported in a large medical cohort of patients with HCM. In addition, the pathophysiological mechanisms underlying MVCR are unknown. The aim of the current study was to assess the prevalence of MVCR in HCM and the clinical profiles of those patients.
Methods
Inclusion criteria
This retrospective single-centre study was conducted over a period of 10 years (2000–2010) in a university hospital with a cardiology department and a cardiac surgery department, with access to all patients’ electronic files. Using the keyword “hypertrophic cardiomyopathy”, we selected all patients with HCM in the database. Once those patients had been identified, a first selection of patients potentially presenting chordal rupture was made using the keywords “mitral regurgitation” and “chordal rupture” to search the database (hospitalization and echocardiographic reports), also including all patients who underwent cardiac surgery. The final diagnosis of chordal rupture was confirmed by systematically reviewing the echocardiographic and surgical reports. We systematically excluded secondary ventricular hypertrophy, particularly caused by hypertension, aortic stenosis, amyloidosis or Anderson-Fabry disease, and only hypertrophic cardiomyopathies believed to be of sarcomeric origin or with a proven morbid mutation on a sarcomeric gene were included in this study.
Evaluation
The general characteristics of the patients were reported, as well as the echocardiographic findings before and after MVCR, plus surgical and histological observations. Echocardiographic measurements were performed in accordance with the guidelines ; obstruction was assessed using continuous-wave Doppler measurement of the instantaneous LVOT gradient, and was considered present when ≥ 30 mmHg; MR was graded, by extension of the regurgitant colour Doppler jet within the left atrium on a scale of 1 to 4, as minimal, mild, moderate and severe, respectively. The lengths (in mm) of the anterior mitral leaflet (AML) and posterior mitral leaflet (PML) were measured blinded to the clinical data, as previously published , on the end-diastolic parasternal long-axis view, after annular hinge points and leaflet tips were identified on video clips. For each leaflet, a mean of three measurements was calculated and compared between the study group ( n = 6), a group of 10 consecutive normal adults (age > 60 years) studied prospectively in our institution, and two groups of clinically stable (without chordal rupture) HCM adult patients (age > 60 years) with ( n = 10) or without ( n = 10) obstruction; these latter groups included the last patients with and without resting echocardiographic obstruction issued from a local hospital HCM registry with available good-quality digital echocardiographic recordings that allowed accurate assessment of leaflet lengths.
Statistical analysis
Continuous variables are expressed as means ± standard deviations (ranges). Leaflet lengths were measured blinded to the clinical data and compared between the three groups using Student’s t- test. Interobserver variability was assessed for leaflet measurement using the coefficient of correlation and the standard error of the estimate according to the Bland-Altman method ( r = 0.98, standard error of the estimate = 0.7 mm). The database was approved by the French authority CNIL (Commission Nationale Informatique et Libertés).
Results
Study group
Among 580 patients with HCM, 502 were systematically followed up in our HCM reference centre, with echocardiographic examinations performed at least every 2 years. Six patients (1%) were diagnosed with MVCR ( Table 1 ): five men and one woman, aged 70.2 ± 4.8 (63–77) years. HCM was sporadic in all cases, and the delay between the diagnosis of HCM and rupture was 16 ± 3.3 (13–18) years. At admission, patients were in sinus rhythm in four cases (67%) and in atrial fibrillation in two cases (33%). Chordal rupture was revealed by dyspnoea in four cases (67%) and by chest pain and syncope in one case (17%), while in one asymptomatic patient it was diagnosed before cardioversion of an atrial fibrillation.
