Atrial Dysfunction in Significant Atrial Functional Mitral Regurgitation: Phenotypes and Prognostic Implications

Abstract

BACKGROUND: Atrial functional mitral regurgitation (AFMR) is associated with increased morbidity and mortality. Left atrial (LA) size and function in AFMR are poorly characterized. We aimed to assess LA function by reservoir strain (LASr) and estimated reservoir work (LAWr) and their impact on outcome in AFMR. METHODS: Consecutive patients at our institution between 2001 and 2019 and with significant (moderate or greater) AFMR were examined. LAWr was estimated as LASr×LA reservoir volume, and patients were grouped by median LASr and LAWr. Outcomes were all-cause death or heart failure hospitalizations. RESULTS: Five hundred fifteen AFMR patients were followed up for 5 (1–17) years. Patients had previously documented atrial fibrillation (AF; 37%), heart failure with preserved ejection fraction (HFpEF) without AF (24%), or both (HFpEF+AF, 39%). LA volume was largest in AF, while LA function parameters were most impaired in the combined HFpEF+AF group. During follow-up, patients with low LASr or LAWr had higher risk of death ( P <0.001) and heart failure hospitalization ( P <0.05). In Cox regression analyses, low LASr and LAWr, but not LA volume or left ventricular function, were associated with a higher risk of death (LASr: hazard ratio, 2.3 [95% CI, 1.6–3.5]; LAWr: hazard ratio, 3.4 [95% CI, 2.4–4.9]; both P <0.001) after adjustment for clinical and echocardiographic confounders. Low LASr and LAWr were strongest associated with death in HFpEF and HFpEF+AF. CONCLUSIONS: LA reservoir function but not LA size is a robust predictor of outcome in significant AFMR. This provides mechanistic insights into the interplay of functional versus geometric LA changes in AFMR.

Left Atrium: A New Prognostic Marker and Therapeutic Target in Secondary Mitral Regurgitation?

“…LA function assessment with estimation of LARS and LA reservoir work (LARW) was more significant compared to size measurement only. [ 15 ] Inciardi et al showed that impaired LA function parameters appear earlier in SMR compared to LA size increase. [ 16 ] In addition, LARS may also be more indicative of LA fibrosis than LA size.…”

Atrial Functional Mitral Regurgitation

“…The latter is influenced by LA size, contractility, and compliance. In their work, Cramariouc et al 6 provide further insight into the LA size and function in those with moderate or greater severity of AFMR. They have described LA mechanics in 3 clinical phenotypes of AFMR: those with AF only, those with HFpEF only, and those with HFpE and AF.…”

“…5 However, these prevalence rates from epidemiological data do not distinguish between those with and without a history of AF. In this issue of the Circulation Cardiovascular Imaging , Cramariuc et al 6 report that 63% of patients with all HFpEF patients and 24% those without history of AF had moderate or greater degree of AFMR. Since echocardiography is the basis to categorize functional MR into ventricular FMR or AFMR, the data from the national echocardiographic database from Australia (NEDA) are also instructive.…”

Impact of Percutaneous Mitral Valve Repair on Left Atrial Strain and Atrial Fibrillation Progression

“…Percutaneous mitral valve repair through transcatheter edge-to-edge repair (TEER) is widely demonstrated to be able to reduce the grade of MR in patients at high surgical risk [ 3 , 4 ]. In the MR untreated scenario, the development of LA cardiomyopathy has been demonstrated to occur, as it progressively determines cellular and structural alterations that predispose to the development of atrial fibrillation (AF) [ 5 , 6 , 7 ]. Similarly, LV assumes a more spherical shape, with broad LV wall stress and end-diastolic pressure, hence leading to a decreased contractile state, with reduced myofiber content and interstitial fibrosis [ 8 , 9 , 10 ].…”

“…Standard deviation,2 Heart failure with preserved ejection fraction;3 Heart failure with mildly reduced ejection fraction;4 Heart failure with reduced ejection fraction; 5 Chronic obstructive pulmonary disease;6 Chronic kidney disease;7 Atrial fibrillation; 8 Society of Thoracic Surgeons;9 Mitral regurgitation; 10 Cardiac implantable electronic devices;11 Implantable cardioverter-defibrillators;12 Cardiac resynchronization therapy device with defibrillator.…”