Undiagnosed coronary ischemia common in CLI; FFR-CT-based strategy may improve outcomes
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In patients with critical limb ischemia, CT-derived fractional flow reserve often detected coronary ischemia, and selective revascularization of ischemia-producing coronary lesions improved outcomes, according to a presentation.
At the International Symposium on Endovascular Therapy, Christopher K. Zarins, MD, emeritus professor of surgery at Stanford University and founder of HeartFlow, presented results of a case-control study of patients with CLI, also known as chronic limb-threatening ischemia (CLTI), who had no cardiac history or coronary symptoms and underwent elective lower-extremity revascularization at a single center from 2017 to 2019.
“The 11% annual mortality [for CLI] is extremely high, and that hasn’t changed over the last 40 years,” Zarins said during the presentation. “In contrast, over that period of time, the annual mortality for patients who present with symptoms of coronary artery disease has declined markedly, and is now 1% to 2% per year. That is an order of magnitude difference. A new strategy to address this issue is based on a noninvasive diagnosis of coronary ischemia using coronary CT angiography and computational analysis of fractional flow reserve.”
The study included 103 patients (mean age, 65 years; 79 men) who had CT and FFR-CT (HeartFlow Analysis) performed before their lower-extremity revascularization to determine whether coronary ischemia was present. Those who had coronary ischemia were evaluated with coronary angiography after their lower-extremity revascularization and some underwent coronary revascularization. Those patients were matched with 120 patients (mean age, 66 years; 83 men) who underwent elective lower-extremity revascularization and received the standard of care and did not have coronary revascularization after their lower-extremity revascularization, Zarins said during the presentation.
The outcomes of interest were MI, CV death and all-cause death at 3 years.
In the FFR-CT group, Zarins said 69% had unsuspected coronary ischemia, defined as FFR-CT of 0.8 or less distal to stenosis, and 58% had severe coronary ischemia, defined as FFR-CT of 0.75 or less distal to stenosis. In addition, 8% had left main ischemia and 40% had multivessel ischemia, and among those with ischemia, the mean FFR-CT was 0.71.
Within 3 months of their lower-extremity revascularization, 46% of the FFR-CT group underwent coronary revascularization, of whom 89% had PCI and 11% had CABG, whereas no patients in the control group had coronary revascularization, Zarins said during the presentation.
At 3 years, the FFR-CT group had greatly reduced risk for MI compared with the control group (4% vs. 23%; HR = 0.14; 95% CI, 0.05-0.4; log-rank P = .001), according to the researchers.
All-cause death rates at 3 years were much lower in the FFR-CT group (11% vs. 28%; HR = 0.32; 95% CI, 0.16-0.64; log-rank P = .001), Zarins said, noting the 3-year mortality rates in the control group were lower compared with those in similar populations from recently published studies.
CV death rates at 3 years were also much lower in the FFR-CT group (3% vs. 18%; HR = 0.14; 95% CI, 0.04-0.48; log-rank P = .001), Zarins said, noting that in the FFR-CT group, 27% of deaths were CV-related compared with 65% of deaths being CV-related in the control group, a difference he attributed to revascularization of ischemia-producing coronary lesions.
“Systematic coronary evaluation of CLTI patients with CT and FFR-CT may help physicians identify coronary ischemia in two out of three patients,” Zarins said during the presentation. “Selective coronary revascularization of ischemia-producing coronary lesions following lower-extremity revascularization reduced adverse cardiac events and improved 3-year survival compared to current standard of care. Prospective randomized trials are indicated to determine the role of FFR-CT in managing the CLTI patients.”
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Zarins CK, et al. Late-Breaking Data and Hot Topics. Presented at: International Symposium on Endovascular Therapy; Jan. 16-19, 2022; Hollywood, Florida (hybrid meeting).
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