Clinical Investigation
Aortic Stenosis
Noninvasive Coronary Flow Reserve Predicts Response to Exercise in Asymptomatic Severe Aortic Stenosis

https://doi.org/10.1016/j.echo.2017.04.005Get rights and content

Highlights

  • ESE is very useful for the management of asymptomatic AS but is not often possible for various extra cardiac reasons

  • Noninvasive coronary flow velocity reserve by transthoracic Doppler echocardiography is independently correlated with exercise capacity and abnormal results on ESE in AS.

  • The noninvasive coronary flow velocity reserve by transthoracic Doppler echocardiography predicts an abnormal ESE with good accuracy (AUC 0.88 ± 0.06, p < 0.01) in patients with AS.

Background

In patients with asymptomatic aortic stenosis (AS), exercise stress echocardiography (ESE) provides additional prognostic information beyond baseline. The coronary flow velocity reserve (CFVR) is impaired in AS, but its link with exertion is unknown in this setting. The aim of this study was to test the hypothesis that CFVR could predict exercise capacity and abnormal exercise test results in AS.

Methods

Noninvasive CFVR and symptom-limited semisupine ESE were prospectively performed the same day in 43 patients with asymptomatic isolated severe AS (mean age, 68.5 ± 11 years; 26% women; mean aortic valve area, 0.8 ± 0.16 cm2; mean left ventricular ejection fraction, 70 ± 7%). CFVR was performed in the distal part of the left anterior descending coronary artery using intravenous adenosine infusion (140 μg/kg/min over 2 min), and ESE was performed at an initial workload of 25 W with a 20- to 25-W increase at 2-min intervals. An abnormal result on ESE was defined as onset of symptoms at <75% of maximum predicted workload, electrocardiographic ST-segment depression ≥2 mm during exercise, increase of systolic blood pressure < 20 mm Hg or decrease in blood pressure, and complex ventricular arrhythmia. Seventeen patients with isolated severe asymptomatic AS, unable to exercise because of extracardiac conditions, served as a comparative group.

Results

Resting, hyperemic left anterior descending coronary artery flow velocity and CFVR (2.45 ± 0.8 vs 2.4 ± 0.8) were similar between the group unable to perform ESE and the ESE group (P = NS for all). Compared with patients with normal results on ESE, those with abnormal results on ESE (n = 22) were older, had higher E/e′ ratios, had higher resting left anterior descending coronary artery flow velocities (39 ± 12 vs 31 ± 8 cm/sec), and had lower CFVR (2.01 ± 0.3 vs 2.85 ± 0.7; P < .01 for all). Furthermore, CFVR was significantly correlated with age, changes in transvalvular pressure gradient and left ventricular ejection fraction with exercise, workload (in watts), and exercise duration (P < .05 for all). After adjusting for other variables, CFVR remained independently correlated with exercise duration, workload, and abnormal results on ESE (P < .01 for all). On receiver operating characteristic curve analysis, CFVR < 2.3 was the best cutoff to predict abnormal results on ESE (area under the curve = 0.88 ± 0.06, P < .01).

Conclusions

In patients with asymptomatic severe AS, noninvasive CFVR is correlated with exercise duration and workload, and low CFVR predicts abnormal results on ESE with good accuracy.

Section snippets

Population

Sixty patients with severe asymptomatic AS (aortic valve area ≤ 1 cm2 or indexed aortic valve area ≤ 0.6 cm2/m2) and preserved LVEF (≥50%) were prospectively enrolled in this two-center study (Compiègne Hospital, Compiègne, France, n = 52; Institut Mutualiste Montsouris, Paris, France, n = 8). Two independent cardiologists blinded to patients’ echocardiographic and biochemical data assessed the absence of symptoms. Patients classified as asymptomatic had to be free of shortness of breath,

Results

The baseline characteristics of patients unable to perform ESE, the ESE group, and each subgroup (normal vs abnormal results on ESE) are summarized in Table 1. Except being older and more frequently women, patients unable to perform ESE had similar characteristics as the ESE group. Coronary flow velocity and hemodynamic measurements at baseline and during adenosine administration are depicted in Table 1 and data related to exercise in Table 2. CFVR was feasible in all patients, with the help of

Discussion

We found in this selective cohort of asymptomatic patients with severe AS and preserved LVEF that noninvasive CFVR was independently correlated with exercise capacity and was associated with abnormal exercise test rsults with good accuracy. Furthermore, the values of CFVR and LAD flow velocity were similar in patients undergoing ESE and those unable to perform ESE because of extracardiac comorbidities.

Conclusions

In patients with asymptomatic severe AS, noninvasive CFVR is independently associated with exercise duration, workload, and abnormal results on ESE with a good accuracy.

References (36)

Cited by (5)

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    One reason involves the characteristics of the enrolled patients. The patients in the present study had a relatively higher age and rate of women and smaller body size compared with those in the previous studies.8,9,11,20-22 In accordance with previous studies assessing AS in the Japanese population,23,24 the present study had lower BSA and smaller LV chamber size.

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