Immediate and late effects of successful percutaneous transvenous mitral commissurotomy on left atrial appendage function in patients with rheumatic mitral stenosis

摘要

Background: Rheumatic mitral stenosis (MS) accounts for up to40% of the valvulopathies in the less developed regions of the world.Since its introduction in 1984 percutaneous transvenous mitralcommissurotomy (PTMC) has been established as a safe and effectivetreatment for rheumatic MS. The left atrial appendage (LAA) isa structure with important pathological implications, which normallyprevents stasis of blood due to its high compliance andcontractility. Chronic pressure and volume overload imposed byMS causes left atrial (LA) and LAA dysfunction leading to reducedblood flow velocities, thereby producing stasis of blood, reduced LAand LAA ejection fraction and atrial fibrillation (AF). These factorspredispose to formation of LA and LAA thrombi in MS and result inthromboembolic episodes. Risk of cerebrovascular accident (CVA)is increased approximately 17-fold in patients with MS with AFand risk of CVA is present even patients of MS in sinus rhythm(SR). Assessment of LAA function is helpful in predicting the riskof thromboembolism. This study was undertaken to evaluate theeffect of PTMC on LAA function by Trans esophageal echocardiography(TEE) Doppler and Doppler Tissue Interface (DTI).Methods: It was a single center prospective observational study.Patients with symptomatic severe MS (Mitral Valve Area <1.5cm2)in SR who underwent a successful PTMC during the period fromMay 2015 to May 2016 were selected. Those patients with AF,LA or LAA thrombus, concomitant significant Aortic valve disease,associated congenital disease, New York Heart Association (NYHA)functional class IV, past PTMC or surgical valvulotomy, pregnancyand critically ill patients were excluded. All the patients underwentclinical, electrocardiographic (ECG), detailed Transthoracicechocardiography (TTE) and TEE to measure fractional area changeof LAA (LAAFAC), LAA early diastolic velocity (LAAEDV), LAA latediastolic velocity (LAALDV) and Tissue Doppler velocity of lateralwall of LAA. TTE, TEE andECGwere done in all patients before PTMC,Immediately after PTMC (within 24 h) and after 6 months of PTMC.Results: A total of 70 patients were included in the study withmean age of 31.8 years. Females accounted for 72.86% (51/70)patients and males were 27.14% (19/70). Mean Wilkins score(WS) was 9.89. Mean MVA pre and Post-PTMC was 0.87cm2 and1.70cm2, respectively. Mean LA volume index pre and post PTMCwas 49 ml/m2 and 46.47 ml/m2, respectively. Mean LAAFAC pre andpost PTMC was 48.6% and 49.12%, respectively. Mean LAAEDV preand post PTMC was 11.9 cm/s and 14.86 cm/sec, respectively. MeanLAALDV pre and post PTMC was 22.76 cm/s and 28.65 cm/s, respectively.Mean DTI early diastolic emptying velocity of LAA pre andpost PTMC were 6.38 cm/s and 9.52 cm/s, respectively. Mean DTILate diastolic emptying velocity of LAA pre and post PTMC were11.67 cm/s and 19.48 cm/s, respectively. There was a significantnegative correlation between Spontaneous Echo Contrast (SEC)grading of LAA and LAA function.Conclusion: Successful PTMC results in significant reductionin the Left Atrial Volume Index, decreases the intensity of LA andLAA SEC, significant increase in the LAAFAC, LAA PW Doppler andDTI velocities and further significant improvement at 6-months offollow-up suggesting continuous structural remodeling of the LAA,leading to improved global and regional LA and LAA function. LAAdysfunction is more severe in patients with SEC than without SECand greater the intensity of SEC more severe is the LAA dysfunction.So, relief ofMSby PTMC not only confers hemodynamic benefits forsymptomatic improvement but may also have a favorable influenceonfuture thromboembolism risk by improving LA andLAAfunction.