Longitudinal left ventricular 2D strain is superior to ejection fraction in predicting myocardial recovery and symptomatic improvement after aortic valve implantation,☆☆,

https://doi.org/10.1016/j.ijcard.2012.06.012Get rights and content

Abstract

Background

Predicting improvement of myocardial function after transcatheter aortic valve implantation (TAVI) for aortic stenosis (AS) remains a challenge. As ejection fraction (EF) may be of limited value in detecting early myocardial dysfunction and predicting outcome, we assessed the potential of echocardiographic longitudinal function in this setting.

Materials and methods

Left ventricular (LV) function was assessed using EF, mitral annular plane systolic excursion (MAPSE), peak longitudinal 2D strain (LS) and strain rate (SR) in101consecutive patients with severe symptomatic AS (age 81 ± 11 years) undergoing TAVI. Echocardiography and assessment of clinical status including NYHA functional class were performed prior and after intervention (median 70 days).

Results

Pre-interventional EF was 57 ± 17% and 32 patients (32%) had an EF < 50% while 58 patients (57%) were found to have an impaired LS. After TAVI there was no significant change in EF. In contrast, LS, SR and MAPSE improved significantly (− 14.0 ± 4.4 vs. − 15.5 ± 4.0%; p = 0.007, 0.68 ± 0.24 vs. 0.78 ± 0.23/s, p = 0.002; and 9.1 ± 3.2 vs. 10.2 ± 3.3 mm, p = 0.006, respectively). Receiver Operating Curve characteristic analysis identified a pre-TAVI LS >  13.3% as the optimal cut-off value for predicting lack of LS recovery post TAVI. There was a marked improvement in NYHA FC after intervention (p = 0.0002). Among the studied echocardiographic parameters LS change correlated closest with NYHA class improvement (r = 0.42, p = 0.0008).

Conclusion

Overall, LS appears to be more sensitive for detecting early myocardial damage in patients with AS compared to conventional echocardiographic parameters. More importantly, pre-interventional LS may identify irreversible myocardial dysfunction and LS improvement correlates with symptomatic improvement after intervention.

Introduction

Optimal timing of intervention in aortic stenosis (AS) remains to be defined [1], [2], [3]. Assessment of myocardial function, especially detecting potentially irreversible myocardial damage, would be crucial with this regard. It would facilitate determination of appropriate timing for early intervention in asymptomatic patients and help to predict the potential benefit of late intervention in more advanced stages of disease. Ejection fraction (EF) has traditionally been used to assess left ventricular function (LVF). Reduced EF at the time of surgical aortic valve replacement (AVR) has been found to be associated with an increased operative risk and worse midterm outcome [4], [5]. Aortic valve replacement is therefore recommended even in asymptomatic patients with an EF of less than 50% [2], [3]. However, it has been demonstrated that EF may remain normal despite impaired longitudinal LVF in AS. EF is indeed often preserved until late in the course of the disease [6] and has been found to be a poor predictor of myocardial fibrosis that in itself is associated with unfavorable outcome after intervention [7]. Longitudinal LVF as determined by various echocardiographic parameters, has been shown to be reduced in patients with AS even when EF is normal [8], [9], [10], [11], [12], [13], [14], [15], [16], [17] and to improve after aortic valve implantation [8], [9], [10], [11], [13], [14], [18], [19]. However, it remains unclear whether such measurements allow to detect irreversible myocardial damage and to predict the lack of symptomatic improvement after intervention. Most of the currently available studies are limited by small patient numbers and rarely addressed the relation to clinical outcome. Speckle tracking echocardiography has recently emerged as a promising tool for assessing myocardial performance. Unlike atrioventricular annular plain systolic excursion, speckle tracking based strain and strain rate measurements can be performed at different positions within the myocardium, thus allowing the measurement of local myocardial function. Furthermore, unlike myocardial tissue velocities measured on tissue Doppler echocardiography 2-D speckle tracking strain measurements are not angle dependent and not affected by tethering effects. Through the combination of longitudinal strain measurements of different myocardial regions, a parameter of global ventricular function can be obtained semi-automatically, facilitating interpretation of results. While previous reports mostly studied surgical AVR, transcatheter aortic valve implantation (TAVI) provides the unique opportunity to eliminate possible detrimental effects of cardiopulmonary bypass and pericardiotomy on myocardial function. We therefore sought to study in a large group of patients undergoing TAVI whether longitudinal LV 2-D strain predicts myocardial recovery and symptomatic improvement after intervention.

Section snippets

Patient population

In total, 101 consecutive patients with severe aortic stenosis who underwent TAVI due to high risk for surgical AVR (mean logistic euroSCORE 24.3 ± 14.6%) were included in this study. Patient characteristics are presented in Table 1. Most of the patients were octogenarians (mean age 81 ± 11 years) and presented with severe symptoms (88% in NYHA functional class III or IV).

Study protocol and echocardiographic measurements

Clinical assessment and comprehensive transthoracic echocardiography were performed prior to intervention (median 19 days) and

Results

Of the 101 patients, 60 underwent transfemoral TAVI, while 41 patients had limited vascular access and required a transapical access. Overall, 95 patients received an Edwards Sapien valve, while 6 patients underwent implantation of an Edwards Sapien XT valve. The 30-day mortality was 10%. Stroke occurred in 5%, while 6% of patients required pacemaker implantation.

Overall, the patients' symptomatic status improved markedly. While 57% of patients were in NYHA class III, 31% in class IV and only

Discussion

Using speckle tracking echocardiography, the current study demonstrates that – although not evident from conventional measures of systolic LV function such as EF – myocardial function is impaired in a considerable portion of patients with severe AS and improves significantly after TAVI. More importantly, these changes are closely related to post-interventional improvement of symptoms and can be predicted from pre-interventional echocardiographic assessment of LV longitudinal strain.

Evaluation

Conclusions

Left ventricular global longitudinal 2D strain appears to be more sensitive in detecting myocardial damage in patients with severe AS than ejection fraction and may gain importance for the optimal timing of intervention as pre-interventional LS appears to predict myocardial recovery after intervention that is related to symptomatic improvement.

Acknowledgment

The authors of this manuscript have certified that they comply with the Principles of Ethical Publishing in the International Journal of Cardiology.

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      Echocardiography is the initial diagnostic test, as it enables assessment of LVEF, regional wall thickness, and LV mass, thus allowing classification of LV geometry into normal, concentric remodeling, concentric hypertrophy, and eccentric hypertrophy. Global longitudinal strain (GLS) is another marker of LV systolic function, which can detect LV dysfunction even in the presence of preserved LVEF and may be a better predictor of myocardial recovery after AVR.24,25 In a cohort of 395 patients with severe AS and preserved LVEF, about 75% of the patients were found to have depressed GLS.26

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    This study was supported by a research grant from the Fördergemeinschaft Angeborene Herzfehler Universität Münster e.V., Germany.

    ☆☆

    R.S. was supported by an educational grant from the Robert-Bosch Stiftung, Germany.

    A.K. was supported by the Deutsche Herzstiftung e. V.

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