UNIVERSITY OF SARAJEVO University Clinical Center Clinic for heart and rheumatic diseases   AKH, University of Wien, Austria STRESS ECHOCARDIOGRAPHY in diagnosis of LOW FLOW - LOW GRADIENT AORTIC STENOSIS   Sokolović S, Mundigler G. Naser N. V. Kongres Kardiologa & Angiologa BiH, Sarajevo 27-29.5.2010.

Epidemiology of Aortic Stenosis AS is common > age 75: 3% SAA Long asymptomatic phase: risk of sudden death low Mortality ↑: exertional chest pain, syncope, breathlessness Mortality up to 12% soon after onset of symptoms Significant AS and LV dysfunction: poor prognoses

Aortic Stenosis Severity of AS with preserved LV : Straightforward to evaluate . Low Flow-Low Gradient AS, with significantly reduced LV : Dg challenge

STRESS TEST Stress modalities: Exercise Sitting bicycle Supine bicycle Threadmill

STRESS TEST Pharmacological Dipyridamole – vasodilating Adenosine – vasodilating Dobutamine: as predominantly a B1-adrenergic stimulating agent:Contractility and HR ↑ Dobutamine: plasma half-life about 2 min.

DST INDICATIONS Better accuracy than exercise ECG INDICATION I: Diagnosis of ischemia: Better accuracy than exercise ECG DSE possible in patients unable to exercise

DST INDICATIONS After AMI: Early wall motion abnormality predicts new event Remote wall motion abnormality predicts multivessel disease. Viability of akinetic area: Sustained improvement: Good prognosis Biphasic response: Good prognosis with revascularisation, poor without.

DST INDICATIONS Indications II: Before PCI / CABG: Significance of stenosis. : only most severe stenosis usually responsive Viability After PCI / CABG: control for restenosis / graft patency

CONTRAINDICATIONS Dobutamine: Uncontrolled hypertension: >220/120 resting Known hypertrophic obstructive cardiomyopathy. Known malignant ventricular arrhythmia Dipyridamole: AV-block COPD Aminofilin

TECHICAL REQUIREMENTS Personnel requirement: doctor and nurse minimum. Patient fasting for 2 hours previously Basic and advanced CPR available Beta blockers discontinued for at least 24 hours ECG & blood pressure monitoring Echocardiography: continuous monitoring. Recording of cine loops at baseline, low dose, high dose, and recovery (optional) Record 3 cycles

TERMINATION Side-by side comparison: Termination criteria: Positive finding by echo: New wall motion abnormality ST depression > 3 mm BP limits: > 220/120 < 70/systolic if good ventricular function any BP drop > 100 mmHg if poor or reduced LV function Arrhythmia: Non-sustained VT or sustained SVT Intolerable symptoms (Angina, nausea) Target Heart rate (> 85% of 220 -age) Maximum dose (40 µg/kg/min + up to 1 mg atropine)

Positive stress echo test: .1 segment with new a-or dyskinesia or . 3 segments with new hypokinesia (= WMSI > 1.25 or increase by 0.25) Additional criteria: Post-systolic thickening Diastolic abnormalities

Diagnostic value OF DST: Sensitivity: 80 -90% If target HR reached Specificity: 80 – 100 % Comparable to perfusion scintigraphy

Definition of LF-LG AS Low gradient AS as severe aortic stenosis (valve area <1.0 cm2) with a transvalvular PG <30 mmHg Low gradient AS occurs in LV systolic dysfunction with low EF, which results in low flow rate across AV Contractile reserve: the ability to increase transvalvular flow and not defined by an improvement in wall motion score or EF

LF-LG AS Low gradient AS: a) caused by critical AS causing LV impairment (fibrosis) b) moderate AS coexisting with another cause of LV impairment: CAD, alcohol, cardiomyopathy The main challenges: - to differentiate these two states - to determine whether the LV is likely to recover after AV surgery

Epidemiology Difficulty to assess true severity of stenosis at low CO PG & calculated AVA flow-dependent LV dysfunction: Presence of low flow rather than significant valve disease Morbidity & Mortality LG AS + low EF, A. surgery is consid 50% do not survive or post op persistent symptoms > 600 AS, pts. >125 mmHg = best postop. survival, pts MPG <35 mmHg had worst (Lund, Circulation) The risk is increased with CAD

DOBUTAMIN STRESS ECHO TEST Assess aortic stenosis with poor LV function Generally low gradient and low area with low dose D Increase in gradient: significant AS increase in aortic valve area: poor hemodynamics non-significant AS Continuous infusion up to 20mcg/kg/min

DOBUTAMIN STRESS ECHO True vs Pseudo-severe AS .. To differentiate between: True vs Pseudo-severe AS

SEVERE AS . AV area remains almost the same after test . PG. MPG & PVsignificantly 

MILD TO MODERATE AS All parameters 

Pseudo-severe AS: . AVA significantly  (0,3cm2) . PG, MPG, PV remain more or less constant despite flow improvement

INDICATIONS FOR DSE In symptomatic patient with AS where echocardiography findings during the rest do not correlate with the symptoms.

DSE

DSE Fixed low-gradient AS: benefit from valve replacement surgery pseudo-AS : valve replacement surgery is not indicated

Patients and Method A male 62 y/o, at least moderate AS with low flow and low TG 72 kg, 172cm, BSA 1,86cm2, DST starting: 2,5mcg/kg/min increasing at 3 min.intervals to 5, 10, 15 and 20 mcg/kg/min Monitoring: 12-lead ECG, RR

Results - LV: normal sized At rest - LV: normal sized - Akinesis: apical anteroseptal, inferoapical, posterorolateral, mid segment of anteroseptal - Hypokinesis: basal and mid posterior, inferior and lateral - EF : 33% - PG: 55mmHg, MPG: 35mmHg - EOA: 0,8cm2. (0,4cm2/cm2)

Contractility improved in: basal, mid lateral segment At Peak: Contractility improved in: basal, mid lateral segment decreased in: basal segment of anterior septum . The other LV wall segments: no change after the test . EF ↑ up to 40% . PG ↑ 64mmHg, MPG 46mmHg . EOA ↑ 0,85cm2.(0,42cm2/cm2) . Pts : free of any symptoms, no any ECG - changes

RESULTS Final diagnosis: Severe aortic stenosis with preserved contractile reserve

DECISION Surgical Valve Replacement

CONCLUSION Dobutamin Stress Echocardiography: - Relevant Dg info in AS of unclear significance & reduced LV function - Better outcome if management decisions based on the result of DST - Moderate AS after DSE: conservative th.

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