Page 31 - Journal of Structural Heart Disease Volume 5, Issue 6

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Original Scientific Article
have poor outcomes [3]. Transcatheter aortic valve re- placement (TAVR) has proven to be an alternative to surgical aortic valve replacement for the treatment of symptomatic severe AS [4].
Randomized clinical trials comparing TAVR with standard-of-care therapies in selected patients with moderate to severe aortic stenosis who are at high- er than normal risk for surgical aortic valve replace- ment have been completed and demonstrated one-year mortality rates for TAVR that were non-infe- rior and in some cases superior to standard surgical therapies [5-8].
To improve risk stratification in TAVR patients, sev- eral studies identified variables associated with poor outcomes. Age, Society of Thoracic Surgery (STS) score, New York Heart Association (NYHA) class, and renal disease were previously identified as prognostic predictors of mortality [9-12]. In addition, paravalvu- lar leak (PVL) and post-procedural renal insufficiency were identified as important risk factors for post-TAVR mortality [13-15].
In long-standing AS, progressive valve narrowing triggers a hypertrophic response that preserves ven- tricular function for many years. Over time, the devel- opment of underlying myocardial fibrosis and myo- cyte injury leads to progression from hypertrophy to heart failure [16, 17]. Once myocardial fibrosis ensues, it provides a structural substrate for arrhythmoge- nicity, playing a major role in sudden cardiac death [18]. Moreover, histological studies demonstrated an association between myocardial fibrosis at the time of aortic valve replacement (AVR) and poor long-term outcomes post-valve replacement [19]. Myocardial biopsy is considered the gold standard for assessing myocardial fibrosis, however, it is an invasive proce- dure that could lead to several complications [20]. Therefore, a need for modern imaging techniques for noninvasive assessment of myocardial fibrosis has emerged.
In this context, two-dimensional speckle track- ing echocardiography (2D-STE) is a promising imag- ing modality that allows the diagnosis of subclinical cardiac impairment including fibrotic changes not detected by conventional echocardiography [21]. 2D-STE provides an assessment of myocardial de- formation and left ventricular torsion [22]. Of all the myocardial deformation parameters, global longitu-
dinal strain (GLS) has been shown to be more clinical- ly useful than circumferential or radial strains [23]. In recent studies, GLS had superior prognostic value to left ventricular ejection fraction (LVEF) in predicting cardiac death, urgent valve surgery or hospitaliza- tions due to heart failure [24]. Additionally, GLS has been shown to be an independent predictor of out- comes in patients with severe asymptomatic AS [25].
More recently, regional or basal longitudinal strain (BLS) has been proven to be a superior predictor of future AVR in asymptomatic AS compared to GLS [26, 27]. Additionally, myocardial fibrosis related to long-standing AS can lead to desynchrony and pro- nounced mechanical dispersion (MD) which has been linked to poor outcomes in these patients [28].
In the early post-TAVR period, a dramatic reduction in the afterload and immediate offloading of the ven- tricle lead to improvement in strain parameters [29]. However, literature describing the prognostic utility of impaired BLS and MD immediately post-TAVR re- mains limited. We hypothesize that in addition to GLS, BLS and MD measured immediately post-TAVR will predict all-cause mortality in severe AS.
Methods
Study design and population
This retrospective study was conducted at Rush University Medical Center (RUMC), Chicago, USA. All patients underwent TAVR after evaluation by a multi- disciplinary heart team. The study was reviewed and approved by the Institutional Review Board at RUMC. From a total of 187 patients with severe aortic ste- nosis (aortic valve area < 1 cm2 , mean gradient > 40 mmHg) who underwent TAVR between January 2012 and March 2018 and had a follow-up echocardiogram performed immediately after TAVR, we excluded pa- tients with incomplete data (n=11), concomitant significant valvular disease (n=10), and poor image quality or arrhythmia at the time of echocardiogra- phy (n=7). A total of 159 patients were included in the current study (Figure 1).
Two-dimensional strain imaging
In this study, myocardial strain parameters were measured by 2D-STE using a vendor-independent software (TomTec, Germany) immediately after TAVR
Hemu M. et al.
Strain Analysis Predicts Mortality in Post-TAVR Patients