Mitral annular disjunction in patients with Marfan syndrome is associated with arrhythmic events, an elevated need for mitral valve intervention, and more aortic events in those with extensive mitral annular disjunction. This is according to research results published in JAMA Cardiology.
The current literature lacks data on the prevalence of mitral annular disjunction — and the associated cardiovascular outcomes and rates of arrhythmia — in patients with Marfan syndrome. Researchers therefore conducted a retrospective, single-center cohort study in order to define the presence of mitral annular disjunction as well as its outcomes in this patient population.
Patients from Ghent University Hospital in Ghent, Belgium, were recruited from January 2004 to December 2019. Outcome measures included aortic events, mitral valve surgery, arrhythmic events, and all-cause mortality.
Eligibility included 154 potential participants with Marfan syndrome; 12 patients were excluded due to poor echocardiographic image quality. In total, the cohort included 142 patients (72 girls and women; median age at first exam, 25 years; age range, 2 to 64 years) who underwent mitral annular disjunction examination; 34% of the cohort were pediatric patients.
Median follow-up time was 12.0 years, and median time between echocardiographic images was 5.8 years. In all, 15 patients had an aortic event before inclusion, 5 had aortic dissection, and 10 had prophylactic aortic surgery; aortic root z scores were available for 89% of patients.
In total, 34% of patients had mitral annular disjunction; this was more frequent among pediatric patients than adult patients (50% vs 26%). After excluding the pediatric population, mitral annular disjunction presence did not increase across age groups. There was no correlation between mitral annular disjunction distance and body surface area urgeryor age, even after pediatric exclusion. No statistically significant increase in mitral annular disjunction distance was noted between the first and most recent echocardiograph in the general cohort.
Patients with mitral annular disjunction were younger at diagnosis (median age, 16 vs 28 years), had more frequent mitral valve prolapse (71% vs 15%), more mitral regurgitation (79% vs 45%), and larger mean mitral annular diameters, as well as increased median indexed left ventricle diameter, lower median left ventricular ejection fraction, and higher aortic root z scores. No differences were seen in PR interval, QRS duration, or QTc duration.
“Mitral annular disjunction presence was independent of any type of FBN1 variant and was not associated with predicted haploinsufficiency or a dominant negative effect at the protein level,” the researchers wrote.
Over the follow-up period, aortic events were seen in 28% of patients; 24% underwent prophylactic aortic surgery and 6% presented with aortic dissection. Aortic events occurred at similar rates in patients with and without mitral annular disjunction (35% vs 25%).
No significant differences in aortic root growth rate were noted after adjusting for age at initial echocardiography.
Arrhythmic events were experienced by 4% of patients. Sustained ventricular tachycardia (VT) and sudden cardiac death (SCD) were present in patients with mitral annular disjunction, but they occurred only in those in the highest severity tertile. Those who had sustained VT and SCD demonstrated no severe mitral regurgitation prior to the event, and 4 of the 5 patients had aortic surgery prior to arrhythmic events.
Study limitations include those inherent to retrospective research, the low frequency of certain observations, and a lack of cardiac magnetic resonance imaging in mitral annular disjunction because imaging was not available for all patients.
“This study of patients with [Marfan syndrome] suggests that the presence of [mitral annular disjunction] is associated with arrhythmic events and a higher need for mitral valve intervention, without significant differences in aortic events,” the researchers concluded. “Assessment of the presence and extent of [mitral annular disjunction] may be useful to better assess the risk of adverse cardiovascular outcomes among patients with [Marfan syndrome].”
Demolder A, Timmermans F, Duytschaever M, Muiño-Mosqurea L, De Backer J. Association of mitral annular disjunction with cardiovascular outcomes among patients with Marfan syndrome. JAMA Cardiol. Published online July 7, 2021. doi:10.1001/jamacardio.2021.2312