Myocardial flow reserve from PET imaging in patients with ischemic HF may identify those with a greater outcome benefit from CABG vs. PCI, according to data presented at the American College of Cardiology Scientific Session.
This study was the second-place winner in the Young Investigator Awards in Clinical Investigations virtual session.
Patients with ischemic HF
Dominik C. Benz, MD, of the department of nuclear medicine at the University of Zurich, and colleagues analyzed data from 254 patients (median age, 65 years) with ischemic HF who were referred for viability testing and stress/rest myocardial perfusion imaging with PET.
The endpoint of interest was any major adverse cardiac event, defined as resuscitated sudden cardiac death, all-cause death, ACS, heart transplantation, late revascularization and HF hospitalization.
Revascularization was performed in 20% of patients. Of these patients, 10% underwent early PCI and 10% underwent early CABG.
During a median follow-up of 3.3 years, major adverse cardiac events occurred in 67% of patients.
Significant predictors of major adverse cardiac events were age (HR per 10 years = 1.2; 95% CI, 1.03-1.4), NYHA class greater than II (HR = 2.18; 95% CI, 1.55-3.07), previous PCI (HR = 1.41; 95% CI, 1.01-1.96), renal insufficiency (HR = 1.74; 95% CI, 1.26-2.42), ejection fraction (HR per 10% = 0.82; 95% CI, 0.71-0.95), scar (HR = 2.38; 95% CI, 1.28-4.45) and myocardial flow reserve (HR = 0.5; 95% CI, 0.36-0.7).
The annual risk for major adverse cardiac events was 14% for myocardial flow reserve of 1.7 or greater, 22% for levels between 1.2 and 1.6 and 33% for levels less than 1.2 (P < .01).
“Cardiac risk, therefore, increased significantly with lowering of myocardial flow reserve,” Benz said during the presentation.
Adding PET imaging parameters on ischemia, scar and hibernating myocardium did not improve outcome prediction. In contrast, the addition of myocardial flow reserve incrementally improved the prediction model. After adjusting for clinical and imaging covariates, researchers found that an increase of myocardial flow reserve of 1 was linked to a 37% RR reduction.
“The question arises: Can this improve risk stratification resulting in better patient management,” Benz said during the presentation.
Annual event rates
Among those with low myocardial flow reserve, patients who underwent early CABG had lower annual rates of major adverse cardiac events compared with those who underwent early PCI (8% vs. 40%; P = .035) or those who did not have any early intervention (8% vs. 33%; P = .018), whereas those who underwent early PCI had similar annual rates of major adverse cardiac events compared with those with no early revascularization (40% vs. 33%; P = .615), according to the researchers.
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