Original article
Acute Improvement in Myocardial Function Assessed by Myocardial Strain and Strain Rate After Aortic Valve Replacement for Aortic Stenosis

https://doi.org/10.1016/j.echo.2006.04.041Get rights and content

Objectives

We investigated whether Doppler tissue imaging (tissue velocity, strain, and strain rate) could be useful to detect subtle left ventricular (LV) dysfunction in patients with aortic stenosis and changes in regional myocardial function after aortic valve replacement (AVR).

Methods

We studied 34 patients (age 69.2 ± 10.4 years) with severe aortic stenosis, 21 of whom underwent AVR. Tissue velocity, systolic strain, strain rate, time to peak strain, and time to peak systolic and diastolic strain rates of basal and midsegments were measured in the apical 4-, 3-, and 2-chamber views before and 2 weeks after AVR.

Results

Strain and systolic strain rate showed the best correlation with LV ejection fraction (r = 0.80 and r = 0.70, respectively, both P < .0001). Early and late diastolic strain rates showed significant correlations with LV mass index (r = 0.45, P < .01; and r = 0.64, P < .0001, respectively) and time to peak strain, to peak systolic strain rate, and to peak early diastolic strain rate with aortic pressure gradient (r = 0.45, P < .01; r = 0.44, P < .01; and r = 0.56, P < .001, respectively) before AVR. Although LV mass index and LV systolic function did not change significantly after 2 weeks (LV mass index, 137 ± 54 vs 125 ± 36 g/m2; LV ejection fraction, 60 vs 58%, both P = not significant), peak strain and strain rates increased (P < .001) and time to peak strain and strain rate shortened after AVR (P < .001). Tissue velocities did not change significantly after AVR.

Conclusions

Strain and strain rate parameters seemed to relate to LV function and aortic stenosis severity. Further, they seemed to be superior to tissue velocity and conventional echocardiography in detecting subtle changes in myocardial function after AVR before LV mass and LV function showed improvement.

Section snippets

Patients

We studied 55 consecutive patients with isolated moderate to severe AS (peak aortic velocity ≥ 3.0 m/s) referred to our institution. Patients with renal insufficiency with plasma creatinine level greater than 1.5 mg/dL, old myocardial infarction, more than mild mitral valve disease or aortic regurgitation, severe pulmonary disease, and segmental LV asynergy were excluded, leaving 34 patients (21 women, mean age 69.2 ± 10.4 years) for the study population. Medication included digitalis (n = 2),

Patient Characteristics

Characteristics for all 34 patients are shown in Table 1. Although LV systolic function was mostly preserved with a mean EF of 58.8%, 3 patients had decreased LV EF (<45%). Clinical and standard echocardiographic parameters before and after AVR are shown in Table 2. Average New York Heart Association class improved from 2.3 ± 0.6 to 1.2 ± 0.5 (P < .001). Heart rate significantly increased 2 weeks after AVR. LV size, wall thickness, and LVMI tended to decrease, but did not reach statistical

Preclinical LV Dysfunction in Patients with AS

In AS, the significant pressure overload increases LV systolic wall stress, which acts as a stimulus for hypertrophy of myocytes. Thus, we usually observe severe LV hypertrophy in patients with advanced AS. Although most of them have good LV EF even with significant LV hypertrophy, there has been myocardial dysfunction through reactive fibrosis.9 Moreover, LV diastolic function has been commonly impaired in the hypertrophied ventricle. Increased myocardial stiffness produces elevation of LV

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Supported in part by a research grant from the Ministry of Health, Labor, and Welfare, Japan.

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