More Sophisticated Imaging Doesn't Necessarily Mean Better Outcomes in Ischemic HF

NEW ORLEANS -- Advanced imaging came up short overall in patients with heart failure (HF) who required further definition of ischemia or viability, although select patients seemed to see some benefit, according to the AIMI-HF trial.

The study's primary endpoint -- a composite of cardiac death, myocardial infarction (MI), resuscitated cardiac arrest, or cardiac hospitalization -- occurred in a similar 31% of those who underwent advanced imaging and 35% in the group who underwent standard single-photon emission CT (SPECT) imaging (HR 0.95, 95% CI 0.71-1.25), reported Lisa Mielniczuk, MD, of the University of Ottawa Heart Institute in Canada.

Nor did advanced imaging, which consisted of cardiac MRI (CMR) or PET, result in a lower incidence of the primary endpoint in patients being evaluated for ischemia (HR 0.86, 95% CI 0.61-1.21), she explained in a presentation at the American College of Cardiology (ACC) annual meeting.

Within the ischemia cohort, however, "there was a marginally significant reduction in cardiac death among patients who had PET imaging compared to SPECT," said Mielniczuk, at 11% versus 18.6%, respectively (HR 0.61, 95% CI 0.38-1.00, P=0.049).

And more patients who had CMR or PET got early revascularization compared with those who underwent SPECT (32% vs 12%, P<0.0001).

For "patients with symptomatic heart failure and reductions in their left ventricular function, if you look for ischemia or of signs of viability, and then act upon revascularizing, then you can make the outcomes better," Edward Fry, MD, of Ascension Health Cardiovascular Service Line in Indianapolis and ACC's 2022-2023 president, explained to MedPage Today.

"The question in this study is when you compare advanced imaging to what is considered standard imaging with SPECT, Are the results superior?" noted Fry. Given that advanced imaging offers better resolution and more high-level information, it would be safe to assume that the findings would make a difference to outcomes, he noted.

"Because this study didn't reach some of the statistical endpoints, I am not sure if it will change clinical practice," said Fry, who was not involved in the trial. He added that "some of the subgroup analyses are consistent with what many people would believe," that advanced imaging leads to earlier revascularization, so the trial does show trends if not statistical significance.

In the ischemia cohort, for example, the cumulative incidence of the primary endpoint was non-significantly lower in those who underwent early revascularization:

• Early revascularization: HR 0.52 (95% CI 0.23-1.15)
• No early revascularization: HR 0.93 (95% CI 0.64-1.36)

"If you had ischemia and you had advanced imaging, you did better, but the overall event numbers were low," said Fry. "It comes back to finding the patients who have heart failure due to ischemic disease and finding the patients who would benefit from revascularization -- this is an age-old question."

The AIMI-HF (Alternative Imaging Modalities in Ischemic Heart Failure) trial was conducted at 15 international sites, most in Canada, but also in Finland, South America, and one site in the U.S.

Overall, 1,069 patients underwent advanced imaging with CMR or PET and 312 underwent standard imaging with SPECT. About 85% were men, the average age was 66-68 years, and over 60% were smokers.

Eligible patients had known or suspected coronary artery disease documented by angiography, previous MI, moderate ischemia or scar with New York Heart Association (NYHA) Class II-IV symptoms and an ejection fraction below 45% or NYHA Class I symptoms and an ejection fraction below 30%.

A total of 271 patients were randomized, while patients who met trial inclusion criteria but were not randomized due to clinical management decisions and still had imaging were included in a registry arm. Propensity score matching was used to adjust for differences in baseline characteristics, study site, and randomization versus registry. Patients were followed for 36 months.

Of note, rates of prescriptions for mineralocorticoid receptor antagonists and ACE inhibitors/angiotensin receptor blockers were low in the study, which started recruitment in 2011 and finished in 2020. As a result, medical therapy was not representative of current clinical practice, said Mielniczuk. That and the small number of patients in the randomized group were noted as trial limitations.

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