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The Role of imaging
1. Unravelling low-flow, low-gradient
aortic stenosis
The Role of Imaging
Prof. Fausto J. Pinto, FESC, FACC
Head, Cardiology Dpt/University Hospital Sta Maria-HPV
University of Lisbon, Portugal
2. • No conflict of interest to declare regarding
this talk.
3. 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
4. Hachita et al. Circulation 2007
512 pts with Severe AS
AVA≤ 0,6 cm2/m2, EF >50%
331 pts
Systolic Vol > 35 ml/m2
181 pts
Systolic Vol ≤ 35 ml/m2
Follow-up 25±19 months
9. Pts with severe AS and low flow Pts com Severe AS, low flow and
normal EF
Ann Throrac Surg 2009
10. 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.
11. 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?
12. Criteria for AS Severity
Guidelines valvular heart disease. ESC, EACTS, 2012
14. Minners J et al. EHJ, 2008
Retrospective study; 2427 pts with preserved EF and AVA ≤ 2 cm2
ØMean gradient 40 mmHg – 0,75 cm2 and peak velocity 4 m/s – 0,8 cm2
16. 333 pts, FE≥ 30% and AVA< 2cm2 – hemodynamics + echo
ØInconsistency of AVA and mean gradient
ØPartially explained by low flow (systolic volume ≤35ml/m2)
Minners J et al. Heart 2010
17. ØThe 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
18. - 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
20. 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)
21. 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
23. 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
29. 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
30. 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
31. 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