Utilization of Coronary CTA and FFR-CT to Reduce Cardiovascular Death in a Critical Limb Ischemia Cohort
Gregory A Stanley, Michelle M Hajostek, Charles S Briggs, Halim Yammine, Hector O CrespoSoto, Tzvi Nussbaum, Frank R Arko, III
Sanger Heart & Vascular Institute/Atrium Health, Charlotte, NC
Background Patients with peripheral arterial disease (PAD) have a significant risk of myocardial infarction and death secondary to concomitant coronary artery disease (CAD). This is particularly true in patients with critical limb ischemia (CLI) who exceed a 20% mortality rate at 6-months despite standard treatment with risk-factor modification. While systematic preoperative coronary testing is not recommended for PAD patients without cardiac symptoms, the clinical manifestations CAD are often muted in patients with CLI due to poor mobility and activity intolerance. Thus, the true incidence and impact of “silent” CAD in a CLI cohort is unknown. This study aims to determine the prevalence of ischemia-producing coronary artery stenosis in a CLI cohort using coronary computed tomography angiography (CCTA) and CT-derived fractional flow reserve (FFR-CT), a non-invasive imaging modality that has shown significant correlation to cardiac catheterization in the detection of clinically relevant coronary ischemia.
Methods Patients presenting with newly-diagnosed CLI at our institution from May 2020—April 2021 were screened for underlying CAD. Included subjects had no known history of CAD, no cardiac symptoms, and no anginal equivalent complaints at presentation. Patients underwent CCTA and FFR-CT evaluation and were classified by the anatomic location and severity of CAD. Significant coronary ischemia was defined as FFR-CT ≤0.80 distal to a >30% coronary stenosis and severe coronary ischemia was documented at FFR-CT ≤0.75, consistent with established guidelines.
Results 169 critical limb ischemia patients were screened; 64 patients (37.9%) had no coronary symptoms and met all inclusion/exclusion criteria. Twenty patients (31.2%) completed CCTA and FFR-CT evaluation. Forty-four patients have yet to complete testing secondary to socioeconomic factors (insurance denial, transportation inaccessibility, testing availability, etc). The mean age of included subjects was 66.7±5.9 years and 13 (65%) were male. Patients presented with ischemic rest pain (n=5, 25%), minor tissue loss (n=12, 60%) or major tissue loss (n=3, 15%). Significant (≥50%) coronary artery stenosis was noted on CCTA in 16 of 20 patients (80%). Significant left main coronary artery stenosis was identified in 2 patients (10%). When analyzed with FFR-CT, 14 patients (70%) had hemodynamically significant coronary ischemia (FFR-CT ≤0.8), and 55% (n=11) had lesion-specific severe coronary ischemia (FFR-CT≤0.75). The mean FFR-CT in patients with coronary ischemia was 0.70±0.07. Multi-vessel disease pattern was present in 50% (n=7) of patients with significant coronary stenosis.
Conclusions The use of coronary CTA-derived fractional flow reserve demonstrates a significant percentage of patients with CLI have silent (asymptomatic) coronary ischemia. More
than half of these patients have lesion-specific severe ischemia which may be associated with increased mortality when treated solely with risk factor modification. CCTA and FFR-CT diagnosis of significant coronary ischemia has the potential to improve cardiac care, perioperative morbidity, and long-term survival curves of CLI patients. Systemic improvements in access to care will be needed to allow for broad application of these imaging assessments should they prove universally valuable. Additional study is required to determine the benefit of selective coronary revascularization in patients with critical limb ischemia.
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