SHA24/061002

VIABILITY IMAGING IS A TEST WITH ADDED COST BUT ALSO GREAT VALUE Abdulaziz Alkhaldi, MD, MSc, FRCSC Consultant Adult & Pediatric Cardiac Surgery, King Abdulaziz Medical City Assistant Professor, King Saud bin Abdulaziz University for Health Sciences Principal Investigator, King Abdullah International Medical Research Center

THE CONCEPT OF MYOCARDIAL VIABILITY Two questions are important: • Effect of viability (presence or absence) on the outcomes of medical therapy (Survival and LV function).

• Effect of viability (presence or absence) on the outcomes of revascularization (Survival and LV function)

WHEN TO CONSIDER VIABILITY IN OUR DECISION MAKING FOR PATIENTS WITH CAD??

•

Not for patients with • clear evidence of ischemia (recurrent angina or demonstrable large area with reversible perfusion defect).

• cardiogenic shock after acute MI. • left main coronary artery stenosis.

• LVEF > 40%

•

Patients with heart failure symptoms, significant LV dysfunction and CAD. • Medical therapy is baseline for all patients.

• The real question is:

“Will they benefit from adding revascularization?”

PATIENT WITH 3 VESSELS DISEASE, SEVERE LV DYSFUNCTION AND HEART FAILURE

POSSIBLE STRATEGY #1 • No need to assess viability, offer CABG + Medical therapy to all patients.

• Overall, better strategy than medical therapy alone to all patients (known since the early trials of CABG vs. Medical e.g. CASS, VA).

• A small sub-group of these patients with End-stage ischemic cardiomyopathy and extensive areas of non-viability will not benefit from the addition of CABG. • Cost of surgery and post operative recovery.

• Added peri-operative mortality / complications (although small).

Circulation. 1975;51:414-420

Circulation. 1993;87:1630-1641

Circulation. 2004;110(suppl 1):II18窶的I22.

Survival rates for patients with CAD and left ventricular ejection fraction less than 40% - Non randomized study: medical therapy vs. CABG

J Thorac Cardiovasc Surg 1998; 116:997-1004

PATIENT WITH 3 VESSELS DISEASE, SEVERE LV DYSFUNCTION AND HEART FAILURE

POSSIBLE STRATEGY #2 • Asses myocardial viability in all patients and only patients with significant viability will get CABG + Medical therapy.

• Concerns: • Patients might be deprived of the benefit of revascularization because of test limitations

LIMITATIONS OF VIABILITY TESTING

TECHNIQUE RELATED LIMITATIONS

J Nucl Med 2007; 48:1135–1146

ANALYSIS RELATED LIMITATIONS ASSUME THAT THERE IS A VIABILITY TEST WITH 100% ACCURACY

• What are the cut-offs of viability associated with each outcome of revascularization (Survival benefit, LV function improvement, symptoms improvement)?

• How will the distribution of viable segments affect outcomes of revascularization?

• How will the interaction of viable segments with the quality of target vessels affect outcomes of revascularization?

• Viable segments with poor targets • Non viable segments with good targets.

CLINICAL USE OF VIABILITY TESTING • Viability testing is not a pathological examination (live vs. dead OR myocardium vs. scar).

• The endpoints used in viability studies after revascularization include: •

Improvement in regional LV function (segments)

• Improvement in global LV function (LVEF) • Improvement in symptoms (NYHA functional class) • Improvement in exercise capacity (metabolic equivalents) • Reverse LV remodeling (LV volumes) • Prevention of sudden death (ventricular arrhythmias) • Long- term prognosis (survival).

Myocardial viability and prognosis in patients with ischemic left ventricular dysfunction.

Bonow RO. Myocardial viability testing and impact of revascularization on prognosis in patients Am Coll Cardiol.

2002; 39: 1159–1162. with coronaryJartery disease and left ventricular dysfunction: a meta-analysis.

Comparison of combination of dipyridamole and dobutamine during echocardiography with Allman KC, Shaw LJ, Hachamovitch R, Udelson JE. thallium scintigraphy with thallium scintigraphy to improve viability detection.

J Am Coll Cardiol. 2002; 39: 1151–1158 Sicari A, Picano E, for Borges AC, Gimelli A, Marzullo P. Infra-low dose dipyridamole test:R, a Varga novel dose regimen selective assessment of myocardial viability Am J Cardiol.

1999; 83: 6–10. by vasodilator stress echocardiography.

Varga A, Ostojic M, Djordjevic-Dikic A,ofSicari R, Pingitore A, after Nedeljkovic I, Picano E.in Accuracy of currently available techniques for prediction functional recovery revascularization Heart J.coronary 1996; 17:artery 629–634. patients with left ventricular dysfunction dueEur to chronic disease: comparison of pooled data.

Bax JJ, Wijns Cornel JH, Visser FC, Boersma E, Fioretti PM. Am W, Heart J. 1981 Nov;102(5):846-57.

J Am Collcontraction Cardiol. 1997; 30: 1451–1460.

Ultrastructural correlates of left ventricular abnormalities in patients with chronic ischemic Myocardial Flow, Glucose Uptake, and Recruitment Inotropic Reserve insurgery.

Chronic Left heart disease: Blood determinants of reversible segmental asynergy of postrevascularization Ventricular Dysfunction: Implications forJ,the Pathophysiology Flameng W, Ischemic Suy R, Schwarz F, Borgers M, Piessens Thone F, Van Ermen of H, Chronic De GeestMyocardial H. Hibernation Bernhard L. Gerber, Jean-Louis J. Vanoverschelde, Anne Bol, Christian Michel, Daniel Labar, William Am Heart J. 1996 Mar;131(3):440-50.

Wijns, and Jacques A. Melin Delineation of myocardial stunning and hibernation by positron emission tomography in Circulation. 1996;94:651-659, advancedmeasurements coronary artery disease. regional myocardial blood flow Positron emission tomographic of absolute Conversano A, Walsh JF, Geltman EM, Perez JE, Bergmann SR,After Gropler RJ. infarction.

Only Hibernating Myocardium Invariably Shows Early Recovery Coronary permits identification of nonviable myocardium in patients with chronic myocardial Revascularization Gewirtz H, Fischman AJ, Gilson M,viability Strauss HW, Alpert NM. Quantitative planar rest-redistribution 201Tl imaging inAbraham detection ofS,myocardial and Bharati Shivalkar, Alex Maes, Marcel Borgers, Jannie Ausma, Ilse Scheys, prediction of improvement in left ventricular function after coronary in patients Johan Nuyts, Luc J Am Coll Cardiol.bypass 1994;surgery 23: 851–859. with severely depressed left ventricular function.

Mortelmans, and Willem Flameng M Ragosta, G A Beller, D D Watson, S Kaul and L Wartery Gimple Relation between contractile reserve and prognosis in patients with coronary Circulation.

1996;94:308-315, disease and a depressed ejection fraction.

P F Cohn, R Gorlin, M V Herman, E H Sonnenblick, H R Horn, L H Cohn and J J Collins, Jr Circulation. 1993;87:1630-1641 doi: 10.1161/01.CIR.87.5.1630 Circulation is published by the American Heart Association, 7272 Greenville Avenue, Dallas, TX 75231 Circulation.

1975;51:414-420 Copyright © 1993 American Heart Association, Inc. All rights reserved.

Print ISSN: 0009-7322. Online ISSN: 1524-4539 doi: 10.1161/01.CIR.51.3.414 Circulation is published by the American Heart Association, 7272 Greenville Avenue, Dallas, TX 75231 Copyright © 1975 American Heart Association, Inc. All rights reserved.

Print ISSN: 0009-7322. Online ISSN: 1524-4539

The online version of this article, along with updated information and services, is located on the World Wide Web at:

CONCLUSION OF ALL NON CONTROLLED TRIALS • Patients with CAD, LVEF < 35% and significant threshold of viable myocardium who get CABG + Medical therapy compared to Medical therapy only will have: • Better survival.

• Better QOL with less cardiovascular events.

• Improved LV function.

• Patients with CAD, LVEF < 35% and NO significant threshold of viable myocardium who get CABG + Medical therapy compared to Medical therapy only will have: • Similar outcomes with the added peri-operative mortality and morbidity of CABG.

â&#x20AC;˘ Meta-Analysis of 24 viability studies using SPECT, PET or DE.

TWO CONTROLLED RANDOMIZED TRIALS

F-18-Fluorodeoxyglucose Positron Emission Tomography Imaging-Assisted Management of Patients With Severe Left Ventricular Dysfunction and Suspected Coronary Disease: A Randomized, Controlled Trial (PARR-2)

Survival (%)

J Am Coll Cardiol. 2007;50(20):2002-2012. doi:10.1016/j.jacc.2007.09.006

Adjusted hazard ratio = 0.62 95% CI 0.42 to 0.93, p = 0.019

Time to First Occurring Outcome Out of the Composite Event

LIMITATIONS OF THE STUDY 1.

Viability testing is not used to direct therapy after randomization. Viability data obtained are only observational.

2.

Viability data were available for only less than 50% of the randomized group.

3.

The differences in baseline characteristics be- tween patients who underwent viability testing and those who did not undergo such testing suggest that at least some patients may have been selected for testing on the basis of clinical factors.

4.

Only 19% of patients were deemed not to have viable myocardium. This small number limited the power of the analysis to detect a differential effect of CABG, as compared with medical therapy

5.

There is possibility that results of viability testing could have influenced subsequent clinical decision making.

6.

Viability data were obtained using either SPECT or Dobutamine Echocardiography. Given the fundamental differences in information provided by these two modalities, analysis of outcomes will have serious limitations. important limitations. (one related to membrane integrity and the other to contractile reserve)

The STICH Trial included 99 sites at 22 countries

IN SUMMARY With all the technique-related and analysis-related limitations of viability testing, studies showed that these tests can distinguish patients who will not improve after revascularization

â&#x20AC;&#x153;Non-Viability Testingâ&#x20AC;?

IDEAL VIABILITY TESTING • Combine 2 or more techniques for assessing viability to improve accuracy.

• The viability analysis will include: • The overall viability score.

• The distribution of viable segments.

• The quality of target vessels feeding the viable segments.

IN CONCLUSION The issue of viability canâ&#x20AC;&#x2122;t be answered by eye balling or simple experience and is not related to whether the vessel is a good target for bypass or not.

The issue of viability should be answered by an objective imaging techniques.

Word of Caution “ Crossing to the other extreme “ • Viability in cases with reasonable LV function (LVEF > 35%) • Non-viable LAD territory with three vessels CAD. • Viability assessment by 2D Echo.

THANK YOU