PHARMACOLOGICAL STRESS ECHOCARDIOGRAPHY Dr Benny J Panakkal Senior
PHARMACOLOGICAL STRESS ECHOCARDIOGRAPHY Dr. Benny J Panakkal Senior Resident Dept. of Cardiology Medical College, Kozhikode
Understanding Basic Concepts
Ischemia Cascade The answer to the Question “Why Echo”
Wall Motion Perfusion Changes More Specific More Sensitive Requires Ischemia May occur without producing Ischemia
Why Echo in comparison to SPECT, PET etc. Low cost Environment friendly No ionizing radiation Equally accurate
Coronary Flow Reserve Angina with ST-T changes WITHOUT Wall Motion Abnormalities Microvascular Ischemia • Syndrome X • LV Hypertrophy
Stressors in Stress Testing
Exercise Stress Testing Treadmill Bicycle Imaging at Peak Stress and during each stage of stress Can accurately measure the time of onset of ischemia Most potent Avoids problem of early resolution of ischemia Prognostically important
Exercise as a Stressor Prototype of Demand driven ischemic stress Hyperventilation Hypercontractility of Normal Walls Drawbacks Excessive Tachycardia Excessive chest wall movement Unable to exercise at all or maximally Circumvented by Pharmacological Stressers
Situations where Pharmacological Stress is preferred to Exercise Stress
Less myocardial dysfunction More blood flow heterogeneity Less blood flow heterogeneity Dobutamine • Sometimes even without wall motion abnormalities • Still supply is sufficient for the demand Dipyridamol
Adverse Effects and Complications
Protocols
Exercise Stress Test Protocol
Dipyridamol Stress Echo Protocol
Ergonovine Stress Protocol for Coronary Vasospasm
Imaging Equipment and Acquisition
Quad screen Format Normal response to Exercise, Dobutamine or Pacing Stress Echo
2 D imaging Harmonic imaging Contrast Echo Follow a Road map Qualitiy issues • Avoid excessive gain settings • Failure to image >1 seg (30%) • Same window, Same view for optimal comparison • Suboptimal visualization (10 -15%) • Perfect Apical 2 chamber view
Contrast Echo and 3 D Imaging Contrast Echo in Stress Echo LV Opacification by micro bubbles Improved Wall motion detection Simultaneous perfusion analysis Targetted approach to assess wall motion Decreased Acquisition periods 3 D Imaging Technically easier
How Contrast Echo improves Endocardial border defintion
Excessive Gain setting spoiling the Endocardial border definition
Comparing Similar looking but totally different views
TDI in Stress Echo TDI or Strain Rate Imaging QRS to onset of Relaxation = 350 – 400 ms Normally interval decreases by 34% ± 10% In Ischemia – 12% ± 18% Diastolic stunning Speckle Tracking Lasts longer than wall motion abnormalities
Applying Strain Rate Imaging in Stress Echo Resting
Applying Strain Rate Imaging in Stress Echo Low dose Dobutamine
Applying Strain Rate Imaging in Stress Echo High dose Dobutamine
The Do(s) and Don’t(s)
Indications of Stress Echo CAD • Diagnosis • Prognosticat ion Eval ua sten tion of osis v seve alve rity Lo isc caliz he ing mi a risk p O Pre sment s asse al n o rti oea t e Ex spn ou dy rule iac to card ogy ol i t e
Special clinical conditions and target endpoints in Stress Echo Regurgitant lesions • Discordant symptoms and severity of lesion • Rise in contractile reserve • Exercise induced peak sytolic pulmonary pressures > 60 mm Hg
Diagnostic and Prognostic value of CFR during Vasodilator testing Only LAD imaged Standalone diagnostic criteria: Structural limitations LCx and RCA very difficult to image and impractical Addition of CFR – ↑ Sensitivity, with modest↓ in Specificity Cannot differentiate between microvascular and macrovascular CAD CFR – Flow (High Neg Pred Value) 2 D – Function (High Pos Pred Value) Used in DCMP too!!
Interpretation
Wall motion scoring and attribution to coronary vascular territories
Interpretation of Pharmacological and Exercise Stress Echo
Stress induced myocardial ischemia – Hallmarks Specific • Worsening of wall motion abnormalities • Development of new wall motion abnormalities Non-Specific • Lack of hyperdynamic motion • Beta Blockers • THR not attained No meaning • Akinetic segment becoming dyskinetic
Adjunctive Diagnostic Criteria LV cavity dilatation Decreased Global LV systolic function TVD or Left Main disease Differential responses to Exercise and Dobutamine Stress Echo
Diagnostic End Points • Max dose of pharmacological agent • Achievement of THR • Akinesis of ≥ 2 LV segements • Severe Chest pain • Obvious ECG positivity • ≥ 2 mm ST shift Submaximal Nondiagnostic End Points • Non tolerable symptoms • Limiting Asymptomatic side effects • Hypertention (BP > 220/120) • Hypotension (BP drop > 40 mm Hg) • Supraventricular Arrythmias • Complex Ventricular Arrythmias • VT • Frequent polymorphic VPC
Dipyridamol Stress Preferred • Hypertension • Atrial and Ventricular Arrhythmias Dobutamine Stress Preferred • • Conduction disturbances Bronchospastic diseases On Xanthine medications Caffeine containing drinks • Tea • Coffee • Cola
Contents of Stress Echo Report
Statistics, Studies The Comparison
Single Centre Analysis ( >50, 000 studies ) – Mayo Clinic Exercise Stress Echo Dobutamine Stress Echo VT 1. 4% 4% VF 1 2 SVT and AF are more common than VT/VF
Diagnostic Accuracy - Overall Sensitivity Specificity Stress Echo 85% 88% Stress SPECT 85% 81% Sensitivities in CAD subtypes SVD DVD TVD Stress Echo 58% 86% 94% Stress SPECT 61% 86% 94% Pellikka PA: Stress echocardiography for the diagnosis of coronary artery disease: Progress towards quantification. Curr Opin Cardiol 20: 395, 2005. Armstrong WF, Zoghbi WA: Stress echocardiography: Current methodology and clinical applications. J Am Coll Cardiol 45: 1739, 2005
Stress Echo as a Prognostic Indicator Cardiac Event : Cardiac Death, Non-fatal MI, Coronary Revascularization Normal Stress Echo – Event Rate < 3% (0. 9% person years of follow up) Predictors of Cardiac Event (TMT) Low effort tolerance LVH Advancing Age Mayo Clinic Study comprising 1325 patients
Predictors among patients with Good Effort Tolerance and Abnormal Stress Echo – Event Rate was 2% person year follow up HR Diabetes 1. 9 Previous MI 2. 4 Increase or No change in LV 1. 6 systolic size Kane GC, Hepinstall MJ, Kidd GM, et al: Safety of stress echocardiography supervised by registered nurses: Results of a 2 -year audit of 15, 404 patients. J Am Soc Echocardiogr 21: 337, 2008
Among patients with a High Pretest Probability for CAD – cardiac event rate At 1 yr At 3 yra Normal Stress Echo 2% 4% Abnormal Stress Echo 17% 25% Elhendy A, Mahoney DW, Burger KN, et al: Prognostic value of exercise echocardiography in patients with classic angina pectoris. Am J Cardiol 94: 559, 2004
Dobutamine Stress Echo in Preop Evaluation and Prognostication Ischemic Threshold Event Rate < 60% THR 43% ≥ 60% THR 9% No Ischemia 0% A Mayo clinic study of 530 patients
Accuracy of different approaches for diagnosis of CAD with Stress Echo Hoffmann R, Lethen H, Marwick T, et al. Standardized guidelines for the interpretation of dobutamine echocardiography reduce interinstitutional variance in interpretation. Am J Cardiol. 1998; 82: 1520– 1524.
Dipyridamol vs Dobutamine Stress Echo
Dipyridamol vs Exercise Stress Echo testing
Dipyridamol vs Exercise Stress Echo testing
Meta analysis of major trials comparing Dipyridamol with Exercise Stess Testing Sensitivity Specificity Accuracy SVD MVD GLOBAL Dipyridamol 66 81 72 92 77 Exercise 72 90 79 82 80
3 D Echo in Stess Testing
Prognostication
Prognostic Value of Inducible Myocardial Ischemia Prognostic value of normal stress echo Normal test – Annual risk of Death = 0. 4% – 0. 9% Metz LD, Beattie M, Hom R, Redberg RF, Grady D, Fleischmann KE. The prognostic value of normal exercise myocardial perfusion imaging and exercise echocardiography: a meta- analysis. J Am Coll Cardiol 2007; 49: 227– 37
Prognostic Value of Inducible Myocardial Ischemia Stress Echo Titration of a Negative Test
Biphasic Response is the single most important response in predicting improvement in LV function in patients with LV dysfunction undergoing revascularization 72% vs <15%
Safety Data
Safety of Pharmacological Stress Echo
Safety of Pharmacological Stress Echo Physical stress with exercise is probably safer than pharmacological testing Lattanzi F, Picano E, Adamo E, Varga A. Dobutamine stress echocardiography: safety in diagnosing coronary artery disease. Drug Saf 2000; 22: 251– 62. Varga A, Garcia MA, Picano E. International Stress Echo Complication Registry. Safety of stress echocardiography (from the International Stress Echo Complication Registry). Am J Cardiol 2006; 98: 541– 3
Special Subsets Valvular Heart Disease
Cut Offs for Diagnosis Contractile Reserve – 20% of stroke volume Valve area improvement to differentiate true from Pseudostenosis – 0. 2% Asymptomatic Sev AS, mean gradient rise on exercise - > 20 mm. Hg
Special Subsets Non Cardiac Surgery
Perioperative Stress Response Hemodynam ic stress Vasospasm Cytokine response Catecholami ne Surge Reduced Fibrinolytic activity Platelet activation Hypercoagulability
When to perform Pharmacological Stress Echo in the context of Perioperative risk stratification Left main or 2 vessel disease High risk category Intermediate risk category with Poor functional capacity • Age < 70 yrs • β blocker therapy suffices • Age > 70 yrs • Revasculariza tion • Only indication for revasculariz ation Peripheral Vascular Disease • Stress Echo positivity does not always mean Revascularizatio n Others • β blockers and Statins
Special Subsets Emergency Department
Randomized muticenter trial - Italy 99% Neg predictive value to r/o ACS Still has drawbacks Patients with negative stress test had early readmission with ACS
Special Subsets Myocardial Viability Assessment
Viable Thickness ≥ 6 mm Scarred Thinned Echodense
Diagnostic Accuracy comparison for Myocardial Viability Assessment Metanalysis Bax et al. 2001 Bax JJ, Poldermans D, Elhendy A, et al. Sensitivity, specificity, and predictive accuracies of various noninvasive techniques for detecting hibernating myocardium. Curr Probl Cardiol. 2001; 26: 142– 186
Examples
Detection of Myocardial Ischemia – Apical wall thickness, improves at low dose but deteriorates and high dose dobutamine stress echo.
THANK YOU
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