Impact of transcatheter aortic valve implantation on mechanical dispersion

Changes and Prognostic Implications of Myocardial Work in Aortic Stenosis Subtypes Undergoing Transcatheter Valve Implantation

Background

Evaluation of left ventricle (LV) systolic function in patients with aortic stenosis (AS) undergoing transcatheter aortic valve implantation (TAVI) is challenging, as LV ejection fraction (LVEF) and global longitudinal strain are afterload dependent. LV global work indices (GWIs) estimate the afterload corrected systolic function.

Objectives

The purpose of this study was to evaluate changes in and prognostic implications of GWIs in subtypes of AS patients before and 1 month after TAVI.

Methods

We included 473 patients undergoing TAVI. GWI was estimated using strain imaging and by adding the aortic valve mean gradient to the systolic blood pressure. The primary endpoint was all-cause mortality, evaluated by Cox proportional hazards and Kaplan-Meier curves.

Results

High gradient, low flow/low gradient, and normal flow/low gradient AS was found in 48%, 27%, and 25%. In patients with LVEF ≥50% delta GWI decreased from preoperative assessment to 1-month follow-up across all subtypes; high gradient (-353 ± 589 mm Hg%, P < 0.01), low flow/low gradient (-151 ± 652 mm Hg%, P = 0.13), and normal flow/low gradient (-348 ± 606 mm Hg%, P < 0.01). For patients with LVEF <50% delta GWI increased; high gradient 127 ± 491 mm Hg%, P = 0.05; low flow/low gradient 106 ± 510 mm Hg%, P = 0.06; normal flow/low gradient 107 ± 550 mm Hg%, P < 0.27. The median follow-up time was 60 months (IQR: 45-69 months). Each step of 100 mm Hg% higher GWI at pre-TAVI assessment was associated with a reduction in all-cause mortality in multivariable analysis (HR: 0.96 [95% CI: 0.92-1.00], P = 0.033).

Conclusions

GWI increases in patients with reduced LVEF after TAVI across AS subtypes whereas GWI decreases in patients with preserved LVEF. Assessment of GWI offers additional prognostic implications beyond LVEF and global longitudinal strain.

Early reverse remodeling by echocardiography after transcatheter aortic valve implantation

INTRODUCTION

Oslo University Hospital is a tertiary center conducting a significant number of transcatheter aortic valve implantation (TAVI) procedures per year. In this follow-up MediPace study, we aimed to investigate early echocardiographic changes in systolic and diastolic functions after TAVI in these patients.

METHODS

All patients enrolled in the previous study were contacted 3 months after TAVI for echocardiographic evaluation. Detailed echocardiography was performed 3.5 ± 1.6 months after TAVI, and compared with baseline evaluations.

RESULTS

A total of 101 patients were analyzed. Mean age was 80.1 ± 6.8 years and 40% of the patients were female. We observed a significant improvement in global longitudinal strain (GLS) (pre-TAVI -16.8 ± 4.1%, post-TAVI -17.8 ± 3.6%, p < .001), with no notable change in LVEF. More than half of the patients (52%) experienced a significant reverse remodeling with ≥10% decrease in left ventricular mass index (LVMi) following TAVI (pre-TAVI 123.6 ± 32.1 vs. 109.7 ± 28.9 g/m2 post-TAVI, p < .001). Pre-TAVI LVMi was a positive predictor, whereas history of HT was a negative predictor of LVMi reduction. There was no significant improvement in diastolic function following TAVI. Highest degree of paravalvular leakage was mild to moderate and was observed in only 2%.

CONCLUSIONS

A significant improvement in GLS and LVMi was found following TAVI. History of hypertension and baseline LVMi were predictors of LVMi change. There was no notable change in diastolic function, including left atrial strain.

Left ventricular mechanical dispersion as a predictor of the need for pacemaker implantation after transcatheter aortic valve implantation: MeDiPace TAVI study

AIMS

Permanent pacemaker (PM) implantation is common after transcatheter aortic valve implantation (TAVI). Left ventricular mechanical dispersion (MeDi) by speckle tracking echocardiography is a marker of fibrosis that causes alterations in the conduction system. We hypothesized that MeDi can be a predictor of the need for PM implantation after TAVI.

METHODS AND RESULTS

Consecutively, 200 TAVI patients were enrolled. Transthoracic echocardiography and electrocardiography examinations were recorded before TAVI to evaluate global longitudinal strain (GLS), MeDi, and conduction disturbances. PM implantation information was obtained 3 months after TAVI. Patients were stratified into PM or no PM group. Mean age was 80 + 7 years (44% women). Twenty-nine patients (16%) received PM. MeDi, QRS duration, existence of right bundle branch abnormality (RBBB), and first-degree atrioventricular (AV) block were significantly different between groups. MeDi was 57 ± 15 ms and 48 ± 12 ms in PM and no PM groups, respectively (P < 0.001). In multivariate analysis, MeDi predicted the need for PM after TAVI independently of GLS, QRS duration, RBBB, and first-degree AV block [odds ratio (OR): 1.73, 95% confidence interval (CI): 1.22-2.45] with an area under the curve (AUC) of 0.68 in receiver operating characteristic (ROC) curves. Moreover, RBBB was an independent predictor of PM need after TAVI (OR: 8.98, 95% CI: 1.78-45.03). When added to RBBB, MeDi had an incremental predictive value with an AUC of 0.73 in ROC curves (P = 0.01).

CONCLUSION

MeDi may be used as an echocardiographic functional predictor of the need for PM after TAVI.

Additive Prognostic Value of Left Ventricular Dispersion and Deformation in Patients With Severe Aortic Stenosis

BACKGROUND

Speckle tracking strain echocardiography allows one to visualize the timing of maximum regional strain and quantifies left ventricular-mechanical dispersion (LV-MD). Whether LV-MD and LV-global longitudinal strain (LV-GLS) provide similar or complementary information in mortality risk stratification in patients with severe aortic stenosis (SAS) remains unknown.

OBJECTIVES

The authors hypothesized that LV mechanical dyssynchrony assessed by LV-MD is associated with an increased risk of mortality and provides additional prognostic information on top of LV-GLS in patients with SAS.

METHODS

A total of 364 patients with SAS (aortic valve area indexed ≤0.6 cm2/m2 and/or aortic valve area ≤1 cm2), LV ejection fraction ≥50% and no or mild symptoms were enrolled. The endpoint was overall mortality.

RESULTS

During a median follow-up period of 41 months, 149 patients died. After adjustment, LV-MD ≥68 ms was significantly associated with an increased risk of mortality (adjusted HR: 1.41; 95% CI: 1.01-1.96; P = 0.044). Adding LV-MD ≥68 ms to a multivariable Cox regression model including LV-GLS ≥-15% improved predictive performance in terms of overall mortality, with improved global model fit, reclassification, and better discrimination. Patients with both criteria had an important increase in mortality compared to patients with none or one criterion (adjusted HR: 2.02; 95% CI: 1.34-3.03; P = 0.001). Interobserver reproducibility of LV-MD was good with an intraclass correlation coefficient of 0.90 (95% CI: 0.72-0.97).

CONCLUSIONS

LV-MD is a reproducible parameter independently associated with an increased risk of mortality in SAS. Increased LV-MD associated with depressed LV-GLS identifies a subgroup of patients with an increased mortality risk. Whether early aortic valve replacement improves the outcome of these patients deserves further studies.

Impact of inter-vendor variability on evaluation of left ventricular mechanical dispersion

PURPOSE

Left ventricular mechanical dispersion (LVMD) is a novel speckle tracking parameter for prognostic assessment of arrhythmic risk prediction. There is growing evidence to support its use in a variety of cardiomyopathic processes. There is paucity of data addressing any presence of inter-vendor discrepancies for LVMD. The aim of this study was to assess inter-vendor variability of LVMD in vendor specific software (VSS) and vendor independent software (VIS) in subjects with preserved and reduced left ventricular function.

METHODS

Fifty-nine subjects (14 normal subjects and 45 subjects with cardiac disease) were recruited and 2D speckle tracking echocardiographic images were acquired on two different ultrasound machines (GE and Philips). LVMD was measured by two different VSS (EchoPac GE and QLAB Philips) and one VIS (TomTec Arena).

RESULTS

There was significant bias and wide limits of agreement (LOA) in the overall cohort observed between two different VSS (17.6 ms; LOA: -29.6 to 64.8; r: .47). There was acceptable bias and narrower LOA with good agreement for LVMD between images obtained on different vendors when performed on VIS (-3.1 ms; LOA: -27.6 to 21.4; r: .75). QLAB LVMD was consistently higher than GE LVMD and TomTec LVMD in both preserved and reduced left ventricular function. LVMD measurements have high intra-vendor reproducibility with excellent inter and intra-observer agreement.

CONCLUSIONS

There was acceptable bias and narrower LOA for LVMD assessment on a VIS. Inter-vendor variability exists for LVMD assessment between VSS. Serial measurements of LVMD should be performed using a single vendor for consistent and reliable results.

Challenges and opportunities in improving left ventricular remodelling and clinical outcome following surgical and trans-catheter aortic valve replacement

Over the last half century, surgical aortic valve replacement (SAVR) has evolved to offer a durable and efficient valve haemodynamically, with low procedural complications that allows favourable remodelling of left ventricular (LV) structure and function. The latter has become more challenging among elderly patients, particularly following trans-catheter aortic valve implantation (TAVI). Precise understanding of myocardial adaptation to pressure and volume overloading and its responses to valve surgery requires comprehensive assessments from aortic valve energy loss, valvular-vascular impedance to myocardial activation, force-velocity relationship, and myocardial strain. LV hypertrophy and myocardial fibrosis remains as the structural and morphological focus in this endeavour. Early intervention in asymptomatic aortic stenosis or regurgitation along with individualised management of hypertension and atrial fibrillation is likely to improve patient outcome. Physiological pacing via the His-Purkinje system for conduction abnormalities, further reduction in para-valvular aortic regurgitation along with therapy of angiotensin receptor blockade will improve patient outcome by facilitating hypertrophy regression, LV coordinate contraction, and global vascular function. TAVI leaflet thromboses require anticoagulation while impaired access to coronary ostia risks future TAVI-in-TAVI or coronary interventions. Until comparable long-term durability and the resolution of TAVI related complications become available, SAVR remains the first choice for lower risk younger patients.