Key result
Narrow-QRS LFLG severe AS with reduced EF associates with higher mechanical dispersion versus NFHG.
Why the study?
It was unknown whether left ventricular mechanical dispersion is associated with low-flow status in patients with severe aortic stenosis categorized by flow-gradient patterns.
Observational (n=316)
No
Left ventricular mechanical dispersion is increased in low-flow low-gradient severe aortic stenosis with reduced LVEF, suggesting it is a marker of systolic myocardial dysfunction rather than aortic stenosis severity.
Answers are grounded in this paper and cite their sources.
May mark myocardial dysfunction in low-flow low-gradient severe AS; hypothesis-generating for risk stratification, needs outcome validation.
Patients with severe aortic stenosis are classified according to flow-gradient patterns. We investigated whether left ventricular (LV) mechanical dispersion, a marker of dyssynchrony and predictor of mortality, is associated with low-flow status in aortic stenosis. 316 consecutive patients with aortic stenosis and QRS duration < 120 ms were included in the retrospective analysis. Patients with severe aortic stenosis (aortic valve area ≤ 1.0 cm 2 ) were classified as normal-flow (NF; stroke volume index > 35 ml/m 2 ) high-gradient (HG; mean transvalvular gradient ≥ 40 mmHg) (n = 79), NF low-gradient (LG) (n = 62), low-flow (LF) LG ejection fraction (EF) ≥ 50% (n = 57), and LF LG EF < 50% (n = 23). Patients with moderate aortic stenosis (aortic valve area 1.5–1.0 cm 2 ; n = 95) served as comparison group. Mechanical dispersion (calculated as standard deviation of time from Q/S onset on electrocardiogram to peak longitudinal strain in 17 left ventricular segments) was similar in patients with NF HG (49.4 ± 14.7 ms), NF LG (43.5 ± 12.9 ms), LF LG EF ≥ 50% (47.2 ± 16.3 ms) and moderate aortic stenosis (44.2 ± 15.7 ms). In patients with LF LG EF < 50%, mechanical dispersion was increased (60.8 ± 20.7 ms, p < 0.05 vs. NF HG, NF LG, LF LG EF ≥ 50% and moderate AS). Mechanical dispersion correlated with global longitudinal strain (r = 0.1354, p = 0.0160) and heart rate (r = 0.1587, p = 0.0047), but not with parameters of aortic stenosis. Mechanical dispersion was similar among flow-gradient subgroups of severe aortic stenosis with preserved LVEF, but increased in patients with low-flow low-gradient and reduced LVEF. These findings indicate that mechanical dispersion is rather a marker of systolic myocardial dysfunction than of aortic stenosis.
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Lavall et al. (2020) conducted an observational in Severe and moderate aortic stenosis with narrow QRS complex (n=316). Low-flow, low-gradient severe aortic stenosis with ejection fraction < 50% vs. Normal-flow, high-gradient severe aortic stenosis was evaluated on Left ventricular mechanical dispersion (p=0.0177). In patients with severe aortic stenosis and narrow QRS complex, mechanical dispersion was significantly increased in those with low-flow low-gradient and reduced ejection fraction compared to normal-flow high-gradient patients.
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