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Myocardial Viability and Survival in Ischemic Left Ventricular Dysfunction Robert O. Bonow, MD On behalf of the STICH T

Myocardial Viability and Survival in Ischemic Left Ventricular Dysfunction Robert O. Bonow, MD On behalf of the STICH Trial Investigators. STICH Financial Disclosures. Background.

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Myocardial Viability and Survival in Ischemic Left Ventricular Dysfunction Robert O. Bonow, MD On behalf of the STICH T

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  1. Myocardial Viability and Survival in Ischemic Left Ventricular Dysfunction Robert O. Bonow, MD On behalf of the STICH Trial Investigators

  2. STICH Financial Disclosures

  3. Background • LV dysfunction in patients with CAD is not always an irreversible process, as LV function may improve substantially after CABG • Assessment of myocardial viability is often used to predict improvement in LV function after CABG and thus select patients for CABG • Numerous studies have suggested that identification of viable myocardium also predicts improved survival after CABG

  4. Limitations of Cohort Studies • Decision for CABG may have been influenced by viability status • No (or inadequate) adjustment for key baseline variables (age, comorbidities) • Cohort studies carried out before modern aggressive medical therapy

  5. STICH Revascularization Hypothesis • The first prospective randomized trial testing the hypothesis that CABG improves survival in patients with ischemic LV dysfunction compared to outcome with aggressive medical therapy • Provides the first opportunity to assess the interaction between myocardial viability and survival in randomized patients who were all eligible for medical management alone and also eligible for CABG.

  6. STICH Viability Hypothesis • In this prospective substudy, we tested the hypothesis that assessment of myocardial viability identifies patients with CAD and LV dysfunction who have the greatest survival benefit with CABG compared to aggressive medical therapy

  7. STICH Viability Hypothesis • All randomized patients were eligible for viability testing with SPECT myocardial perfusion imaging or dobutamine echo. • Viability testing was optional at enrolling sites and was not a prerequisite for enrollment.

  8. STICH Viability Hypothesis • SPECT protocols: • • Thallium-201 stress-redistribution-reinjection • • Thallium-201 rest-redistribution • • Nitrate-enhanced Tc-99m perfusion imaging • Dobutamine echo protocols: • • Staged increase in dobutamine starting at • 5 μg/kg/min

  9. STICH Viability Hypothesis • Criteria for myocardial viability were prospective and pre-specified • SPECT: • 17 segment model • ≥11 segments manifesting viability based on relative tracer activity • Dobutamine echo: • 16 segment model • ≥5 segments with dysfunction at rest manifesting contractile reserve with dobutamine

  10. STICH Viability Hypothesis Primary endpoint: ▪ All-cause mortality Secondary endpoints: ▪ Mortality plus cardiovascular hospitalization ▪ Cardiovascular mortality Intention-to-treat analysis

  11. Patients randomized in STICH Revascularization Hypothesis 1212 Patients with myocardial viability test Patients with no myocardial viability test 594 618 Unusable test • Timing • Poor quality Patients with no usable myocardial viability test 17 611 Patients with usable myocardial viability test 601

  12. Patients randomized in STICH Revascularization Hypothesis 1212 SPECT n=471 Dobutamine echo n=280 150 321 130 Patients with no usable myocardial viability test 611 Patients with usable myocardial viability test 601 114 Nonviable 487 Viable

  13. Baseline Characteristics Patients With and Without Myocardial Viability * * Significant covariates in risk model: Age, renal function, heart failure, ejection fraction, CAD index, mitral regurgitation, stroke

  14. Myocardial Viability and Mortality 1.0 Without viability With viability Variables associated with mortality 0.8 HR 95% CI P 0.64 0.48,0.86 0.003 0.6 Mortality Rate 50% 0.4 33% 0.2 0.0 0 1 2 3 4 5 6 Years from Randomization Without viability With viability 114 99 85 80 63 36 16 487 432 409 371 294 188 102

  15. Myocardial Viability and Mortality

  16. Myocardial Viability and Cardiovascular Mortality 1.0 Without viability With viability 0.8 HR 95% CI P 0.61 0.44,0.84 0.003 0.6 43% Cardiovascular Mortality Rate 0.4 29% 0.2 0.0 0 1 2 3 4 5 6 Years from Randomization Without viability With viability 114 99 85 80 63 36 16 487 432 409 371 294 188 102

  17. Myocardial Viability and Mortality + CV Hospitalization 1.0 Without viability With viability 82% 0.8 HR 95% CI P 0.59 0.47,0.74 0.001 0.6 63% Mortality and CV Hospitalization Rate 0.4 HR 95% CI P 0.59 0.47,0.44 <0.001 0.2 0.0 0 1 2 3 4 5 6 Years from Randomization Without viability With viability 114 56 41 34 22 14 5 487 327 284 238 166 94 41

  18. Patients with viability tests 601 Patients with myocardial viability 487 114 Patients without myocardial viability 243 244 60 54 CABG 47.4% MED 49.9% CABG 50.1% MED 52.6%

  19. Baseline Characteristics * * * Significant covariates in risk model: Age, renal function, heart failure, ejection fraction, CAD index, MR, stroke

  20. Myocardial Viability and Mortality Without Viability With Viability 1.0 MED (95 deaths) CABG (83 deaths) MED (33 deaths) CABG (25 deaths) 0.8 56% 0.6 Mortality Rate 35% 0.4 42% 31% 0.2 0.0 0 1 2 3 4 5 6 0 1 2 3 4 5 6 Years from Randomization Years from Randomization MED CABG 60 51 44 39 29 14 4 243 219 206 179 146 94 51 54 48 41 41 34 22 12 244 213 203 192 148 94 51

  21. Myocardial Viability and Mortality Without Viability With Viability 1.0 MED (95 deaths) CABG (83 deaths) MED (33 deaths) CABG (25 deaths) 0.8 56% 0.6 Mortality Rate 35% 0.4 42% 31% 0.2 0.0 0 1 2 3 4 5 6 0 1 2 3 4 5 6 Years from Randomization Years from Randomization Subgroup Without viability With viability N Deaths HR 95% CI 114 58 0.70 0.41, 1.18 487 178 0.86 0.64, 1.16 Interaction P value 0.528 0.25 0.5 1 2 CABG better MED better

  22. Interaction of Viability and Treatment on CV Outcomes

  23. STICH Viability Hypothesis Limitations: • Lack of viability data in all patients; patients represent a subpopulation of STICH • Analysis limited to SPECT and dobutamine echo, not PET or cardiac MRI

  24. STICH Viability Hypothesis • STICH represents the largest report to date relating myocardial viability to clinical outcomes of patients with CAD and LV dysfunction • … and is the first to assess these relationships prospectively among patients who were all eligible for CABG as well as optimal medical management alone

  25. STICH Viability Hypothesis STICH results: • …demonstrate a significant association between myocardial viability and outcome, but this association is rendered non-significant when subjected to a multivariable analysis that includes other prognostic variables. • …fail to demonstrate a significant interaction between myocardial viability and medical versus surgical treatment with respect to mortality, whether assessed according to treatment assigned (intention to treat) or to the treatment actually received.

  26. STICH Viability Hypothesis • Implications: • In patients with CAD and LV dysfunction, assessment of myocardial viability does not identify patients who will have the greatest survival benefit from adding CABG to aggressive medical therapy Full report available at www.NEJM.org

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