Impact of left ventricular fibrosis and longitudinal systolic strain on outcomes in low gradient aortic stenosis

Background

The clinical utility of comprehensive cardiac magnetic resonance (CMR) for the assessment of myocardial structure and function remains unknown in patients with low gradient (LG) aortic stenosis (AS).

Purpose

This study sought to compare CMR characteristics of myocardial structure and function according to different flow / gradient patterns of AS: classical low flow LG (LFLG); paradoxical LFLG; normal flow LG; and high gradient, and to evaluate their impact on the outcomes of these patients.

Methods

International multicentric prospective study included 147 patients with LG moderate to severe AS and 18 patients with high gradient severe AS who underwent comprehensive CMR evaluation of left ventricular global longitudinal strain (LVGLS), extracellular volume fraction (ECV), and late gadolinium enhancement (LGE).

Results

Patients with classical LFLG (n=90) had more LV adverse remodeling and impaired longitudinal function including higher ECV, and higher LGE and volume, and worst LVGLS, compared to other patterns of AS. Over a median follow-up of 2-years, 43 deaths and 48 composite outcomes of death or heart failure hospitalization occurred in LG AS patients. As LVGLS or ECV worsened, risks of adverse events also increased (per tertile of LVGLS: HR [95% CI] for mortality, 1.50 [1.02–2.20]; p=0.04; HR [95% CI] for composite outcome, 1.45 [1.01–2.09]; p<0.05) (per tertile of ECV: HR [95% CI] for mortality, 1.63 [1.07–2.49]; p=0.02; HR [95% CI] for composite outcome, 1.54 [1.02–2.33]; p=0.04). LGE presence was also associated with higher mortality (HR [95% CI], 2.27 [1.01–5.11]; p<0.05) and risk of the composite outcome (HR [95% CI], 3.00 [1.16–7.73]; p=0.02). The risk of all-cause death and of the composite outcome increased in proportion to the number of impaired components (i.e. LVGLS, ECV and LGE) (Figure) with and without adjustment for age, true severe AS, classical LFLG, and aortic valve replacement as a time-varying covariate.

Conclusions

In this international multicentric study of LG AS, comprehensive CMR assessment of myocardial structure and function provides independent prognostic value that is cumulative and incremental to clinical and echocardiographic characteristics.

Funding Acknowledgement

Type of funding sources: None.

Use of the Valve Visualization on Echocardiography Grade Tool Improves Sensitivity and Negative Predictive Value of Transthoracic Echocardiogram for Exclusion of Native Valvular Vegetation

BACKGROUND

Transesophageal echocardiography (TEE) remains the preferred test to rule out infective endocarditis (IE) but is resource intensive and carries risk. Multiple studies report low sensitivity of transthoracic echocardiography (TTE) for detection of IE; however, these studies did not account for TTE quality. We test the validity of a simple valve visualization grading tool to stratify TTEs by quality and determine whether a high-quality TTE may be used to exclude valvular vegetation and forgo the need for TEE.

METHODS

The Valve Visualization on Echocardiography Grade (VEG) tool scores the TTE from 0 to 10 based on leaflet visualization and valve leaflet clarity. The tool was retrospectively applied to 309 sequential patients who underwent both TTE and TEE at an academic teaching hospital between 2011 and 2015. The TEE report was the gold standard for presence or absence of vegetation. Patients with prosthetic valves and pacemaker wires were excluded. Sensitivity of TTE for detecting vegetation was calculated at each VEG score, and the optimal cutoff was identified.

RESULTS

A total of 309 patients were included in the analysis. Among the 216 negative TTEs, 19 (9%) had a positive TEE. The median VEG score was 4. A VEG score cutoff >6 provided optimal sensitivity and was used as the cutoff. Overall, 75 (25%) patients had a VEG score >6, and 234 (75%) had a score ≤6. Sensitivity and negative predictive value for IE were higher in the VEG >6 versus VEG ≤6 group (sensitivity 96% vs 66%, negative predictive value 97.5% vs 90%; P < .05). The false-negative rate was lower (2.5% vs 10%; P = .04) in VEG > 6 versus VEG ≤ 6 groups, respectively.

CONCLUSIONS

Leaflet visualization and valve leaflet clarity are important components in the TTE evaluation of patients with suspected IE. This study demonstrates that the better the valve leaflets are visualized on TTE (as represented in this population by a score >6), the higher the confidence one can have that the TTE will not be falsely negative for vegetation(s) when vegetation(s) are not noted on these TTEs. If validated in future prospective studies, this may reduce the need to perform an invasive TEE in selected patients undergoing evaluation for native valve IE.

6097Aminoterminal proB-type natriuretic peptide: a key parameter to optimise therapeutic management of low-flow, low-gradient aortic stenosis

Background

B-type natriuretic peptide (BNP) and aminoterminal-proBNP (NT-proBNP) are well established surrogates of LV function impairment. However, data are scarce regarding their prognostic value to risk-stratify patients with classical low-flow, low-gradient aortic stenosis (LFLG-AS, with low left ventricular [LV] ejection fraction).

Methods

The TOPAS study is a prospective observational cohort of 240 patients with aortic valve area <0.6 cm2/m2, mean gradient<40 mmHg and LVEF<50%. True severe AS was adjudicated using flow independent grading schemes.

Results

BNP significantly predicted one-year (area under the receiver operating-characteristic curve [AUC]) 0.62±0.04, p=0.026) but not three-year mortality. After adjustment for the severity of AS, initial treatment (aortic valve replacement [AVR] vs. conservative management [ConsRx]), age, sex and the EuroSCORE (Model#1), BNP-ratio>550 pg/ml had a trend to predict time to death (HR=2.14 [1.00–4.58], p=0.05). In contrast, NT-proBNP ratio significantly predicted both one and three-year mortality (AUC=0.67±0.04 and 0.66±0.05, both p=0.001), and independently predicted time to death (HR=1.39 per 1 unit of Log transformed NT-proBNP [1.11–1.74], p=0.004). In a head-to-head comparison (108 patients with both biomarkers), the AUCs to predict one and thre-year mortality were significantly higher with NT-proBNP versus BNP (p<0.009). NT-proBNP but not BNP independently predicted mortality and significantly improved Model#1 (Likelihood ratio test Chi2=15.95, p<0.001). The category-free net reclassification index of NT-proBNP was 0.71 (p=0.008) versus 0.38 (p=0.15) for BNP. Furthermore, there was a marked survival benefit associated with AVR in patients with NT-proBNP ≥1700 pg/ml (adjusted hazard ratio (aHR) associated to AVR vs conservative management=0.52 [0.31–0.85], p=0.009), while those<1700 pg/ml had excellent one-year survival under ConsRx (only one death [4.5±4.4%] at one year as compared to 23 [37±6.2%] for ConsRx-NTproBNP>1700, aHR=0.11 [0.01–0.83], p=0.033). The survival benefit associated with AVR interacted with NT-proBNP (p<0.001) but not with true or pseudosevere AS (p=0.53 for interaction), suggesting that NT-proBNP might identify moderate AS patients but sufficiently severe valvulo-ventricular disease to justify AVR.

Survival according to NT-proBNP and AVR

Conclusion

NT-proBNP appears to be an excellent biomarker for the clinical purpose of risk-stratifying classical LFLG-AS. A threshold of 1700 pg/ml i.e. close to the diagnostic threshold for heart failure in acute dyspnea, was a strong independent determinant of the survival benefit associated with aortic valve replacement. Our findings suggest that NT-proBNP should be preferred over BNP.

Acknowledgement/Funding

Canadian Institute of Health Research

6099Impact of aortic valve replacement on outcomes of patients with low-flow, low-gradient moderate aortic stenosis

Background

Aortic valve replacement (AVR) is recommended for patients with low-flow, low-gradient (LFLG) and true-severe aortic stenosis (TSAS). However, there is very few data on the potential benefit of AVR in patients with LFLG pseudo-severe (i.e. moderate) AS (PSAS).

Methods

Consecutive patients with aortic valve area ≤0.6 cm2/m2, mean gradient <40 mmHg were prospectively recruited in a multicenter observational cohort study. The patients were categorized in TSAS vs. PSAS using previously reported thresholds of flow-independent parameters of AS severity (projected valve area at normal flow rate ≤1.0 cm2 and/or aortic valve calcium score by CT >1200 AU in women and >2000 AU in men). To account for between-treatment-group differences, inverse probability-of-treatment weighting was combined to Cox proportional hazards regression.

Results

Among the 430 patients included in this study, 297 (69%) were classified as TSAS and 274 (57%) underwent AVR. Of note, 21% of the patients treated by AVR were classified as PSAS. In patients managed conservatively (ConsRx), 52% had PSAS and 48% TSAS. During a median follow-up of 28 months [8–60], 198 patients died. The adjusted weighted hazard ratio (awHR) of death associated with AVR as compared to ConsRx was 0.42 [0.24–0.73] (p<0.0001, Figure1-Panel-A). This survival benefit associated with AVR was observed not only in patients with TSAS but also in those with PSAS (awHR: 0.29 [0.12–0.70]; p=0.006, Figure1-Panel-B).

Figure 1

Conclusion

The results of this study suggest that AVR is associated with a survival benefit not only in LFLG patients with TSAS but also in those with PSAS. Randomized trials are needed to confirm the benefit of AVR in patients with moderate AS and depressed LV systolic function.

Acknowledgement/Funding

Canadian Institute of Health Research

Paravalvular Regurgitation After Transcatheter Aortic Valve Replacement: Is the Problem Solved?

Paravalvular regurgitation is a frequent complication after transcatheter aortic valve replacement and its association with worse outcomes depends on the degree of its severity. Despite substantial improvement in transcatheter heart valve design, sizing and implantation technique, moderate or severe paravalvular regurgitation still occurs in 2% to 7% of patients and is associated with a more than 2-fold increase in mortality. This review provides a state-of-the-art approach to (i) paravalvular regurgitation prevention by optimizing patient selection, valve sizing, and positioning and (ii) the detection, quantitation and management of paravalvular regurgitation during and after valve implantation.