the role of imaging
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Unravelling low-flow, low-gradient aortic stenosis
The Role of ImagingProf. Fausto J. Pinto, FESC, FACC
Head, Cardiology Dpt/University Hospital Sta Maria-HPV
University of Lisbon, Portugal
Philippe Pibarot , Jean G. Dumesnil
Different Patterns of Severe AS According to Flow, Gradient, and LV Geometry
Journal of the American College of Cardiology, Volume 60, Issue 19, 2012, 1845 - 1853
Hachita et al. Circulation 2007
512 pts with Severe AS AVA≤ 0,6 cm2/m2, EF >50%
331 ptsSystolic Vol > 35 ml/m2
181 ptsSystolic Vol ≤ 35 ml/m2
Follow-up 25±19 months
These studies suggest…
• A significant proportion of pts with reduced AVA may have low flow and low gradient despite preserved EF.
• A pattern of increased afterload, concentric LVH and impaired survival suggests a more advanced stage of AS.
• This situation may be under diagnosed and not be timely treated with surgery.
Questions
• What is the mechanism underlying low flow/low gradient in pts with severe AS and preserved EF?
• Can we identify those pts using the currently available techniques and criteria? – Inconsistencies of echocg for the current criteria? – Different severity criteria?
• What is the prognosis and treatment?
Minners J et al. EHJ, 2008
Retrospective study; 2427 pts with preserved EF and AVA ≤ 2 cm2Ø Mean gradient 40 mmHg – 0,75 cm2 and peak velocity 4 m/s – 0,8 cm2
333 pts, FE≥ 30% and AVA< 2cm2 – hemodynamics + echoØ Inconsistency of AVA and mean gradientØ Partially explained by low flow (systolic volume ≤35ml/m2)
Minners J et al. Heart 2010
Ø The underestimation of LVOT is one of the factors that may lead to a false diagnosis of low flow
Estimated area 381 mm2 Estimated area 581 mm2
Inadequate measurement of LVOT/ellipsoid configuration (eco 3D, CT, MRI)Utsunomiya et al. Int J Cardiol 2011
- Handgrip and fenilefrine- Presence of HTN pseudodiagnosis of low flow impair the AoV resistance and AVA, regardless of aortic compliance; in addition the gradient has an inconsistent variability
Litle SH et al. Heart 2007
1. Increased vascular afterload
• Increase of the vascular afterload (age, atherosclerosis) and valvular– Symptoms in pts with moderate AS– Increased valvulo-arterial impedance and
impaired vascular compliance associated with LV dysfunction in AS in the older pts (Briand etl, JACC 2005)
– Increased in pts with severe AS and low flow (Hachita et al 2009)
2. Diastolic Dysfunction
• Geometry: – Small size LV (<50 mm, < 60 ml/m2),– Hypertrophy
• Diastolic Compromise• Incremental effect if associated to
increased systemic afterload + valvular
Dumesnil et al. Eur Heart J 2010
AS / low flow and 2D strain
120 pts with severe AS, EF > 50%, with normal vs low flow Pts with low flow had impaired longitudinal strain = LV Dysfunction
Mielot. EHJ 2009
uThe low flow/low gradient group (9%), differed significantly from the other groups:
uLess HTN but more diabetesuIncreased afterload (>valvulo-arterial
impedance )uImpaired basal LV longitudinal strain uImpaired radial strain
How to Assess - I• 1. Exclude pitfals
– LVOT measurement,– Assess EF by two different – Use CMR and CT (LVOT; LV function)
• 2. Assess the indices of myocardial deformation• 3. Confirm low flow low output; • 4. Assess biomarkers
Dumesnil et al. EHJ 2010
How to Assess - II• 4.Additional indices
of AS severity– Energy loss index;
Ao<30mm– Increased resistance– AoV Calcification +++
• 5. Conditioning Factors:– > valvulo-vascular
impedance – < aortic compliance – Small and hypertrophic LV– Females
Conclusions
• Severe AS with low flow and preserved EF may represent up to 25% of the AS Population
• Medical treatment is associated with an increased event rate and mortality but surgery can improve the diagnosis
• Its identification and diagnosis are crucial• Imaging plays a central role in the correct
diagnosis and patient management
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