Natural progression of low-gradient severe aortic stenosis with preserved ejection fraction

Echocardiographic findings on aortic stenosis: an observational, prospective, and multi-center registry

BACKGROUND

The aim of this aortic stenosis registry was to investigate the changes of routine echocardiographic indices and strain in patients with moderate-to-severe aortic stenosis over a 6-month follow-up period.

METHODS

Our aortic stenosis registry is observational, prospective, multicenter registry of nine countries, with 197 patients with aortic valve area less than 1.5 cm². The enrolment took place from January to August 2017. We excluded patients with uncontrolled atrial arrhythmias, pulmonary hypertension or cardiomyopathies, as well as those with hemodynamically significant valvular disease other than aortic stenosis. We included patients who did not require intervention and who had a complete follow-up study.

RESULTS

In patients with preserved ejection fraction, left ventricular mass has significantly increased between baseline and follow-up studies (218 ± 34 grams vs 253 ± 29 grams, p = 0.02). However, when indexed to body surface area, there was no significant difference. Left ventricular global longitudinal strain significantly decreased (-19.7 ± -4.8 vs (-16.4 vs -3.8, p = 0.01). Left atrial volume was significantly higher at follow-up (p = 0.035). Right ventricular basal diameter and mid-cavity diameter were greater at the follow-up (p = 0.04 and p = 0.035, respectively). Patients with low-flow low-gradient aortic stenosis had significantly lower global longitudinal strain (-12.3% ± -3.9% vs -19.7% ± -4.8%, p = 0.01).

CONCLUSION

Left atrial dilatation is one of the first changes to take place in low-flow low-gradient aortic stenosis patients even when left ventricular dimensions and function remains intact. Global longitudinal strain is an important determinant of left ventricular systolic and diastolic dysfunction and right ventricular function is an important parameter of aortic stenosis assessment. Accordingly, our registry has further shed the light on these indices role as multisite follow-up of aortic stenosis.

Progression of Low-Gradient, Low-Flow, Severe Aortic Stenosis With Preserved Left Ventricular Ejection Fraction

Low-gradient (LG), low-flow (LF), severe aortic stenosis (AS) with preserved ejection fraction (PEF) is considered by some authors as an advanced form of AS associated with very poor outcome. The aim of this Doppler echocardiographic study was to investigate changes over time in the hemodynamic severity of LG/LF AS with PEF. We retrospectively identified in 2 academic centers 59 patients who had 2 Doppler echocardiographic examinations without an intervening event. After a median follow-up of 2 (interquartile range [IQR] 1.3 to 3.5) years, progression was observed with increase in mean Doppler gradient (MDG; from 27 [23 to 32] to 37 [28 to 44] mm Hg; p <0.001), peak aortic jet velocity (from 330 [314 to 366] to 373 [344 to 423] cm/s; p <0.001), and decrease in aortic valve area (AVA; from 0.73 [0.63 to 0.92] to 0.64 [0.56 to 0.75] cm(2); p = 0.001). Annual rates were, respectively, 8 mm Hg/year, 36 cm/s/year, and -0.04 cm(2)/year. EF decreased from 62% (55% to 69%) to 58% (51% to 65%), p = 0.001. At follow-up, MDG increase was observed in 51 patients (86%), and 24 patients (41%) acquired the features of classical high-gradient (HG) severe AS (MDG ≥40 mm Hg and peak aortic jet velocity ≥400 cm/s). There were no differences as regard to baseline hemodynamic parameters between patients who displayed ≥5 mm Hg MDG increase and those in whom such increase was not observed. In conclusion, most patients with LG/LF AS with PEF exhibit over time increase in MDG and decrease in AVA with slight EF impairment. This result suggests that LG/LF AS with PEF is an intermediate stage between moderate AS and HG AS rather than an advanced form of the disease.