Lipid-Rich Necrotic Core in the SFA and PAD Events

Study Questions:

What are the associations of the presence of lipid-rich necrotic core (LRNC) in the proximal superficial femoral artery (SFA) with lower extremity peripheral artery disease (PAD) event rates and systemic cardiovascular event rates?

Methods:

Participants with ankle-brachial index (ABI) <1.00 were identified from Chicago medical centers and followed annually. Magnetic resonance imaging (MRI) was used to characterize SFA atherosclerotic plaque at baseline. Medical records for hospitalizations and procedures after baseline were adjudicated for lower extremity revascularization, amputation, critical limb ischemia, and also for new coronary events, ischemic stroke, and mortality.

Results:

Of 254 PAD participants, 62 (24%) had LRNC and 149 (59%) had calcium in the SFA at baseline. Cox regression analyses were adjusted for age, sex, race, comorbidities, baseline ABI, and other confounders. SFA LRNC was associated with an increased incidence of the combined outcome of lower extremity amputation, critical limb ischemia, ABI decline >0.15, and revascularization at 47-month follow-up (hazard ratio [HR], 2.18; 95% confidence interval [CI], 1.27-3.75; p = 0.005). The association of SFA LRNC with PAD events was maintained even when this combined outcome excluded lower extremity revascularization (HR, 2.58; 95% CI, 1.25-5.33; p = 0.01). LRNC in the SFA was not associated with all-cause mortality, acute coronary events, or stroke.

Conclusions:

The authors concluded that among people with PAD, LRNC in the SFA was associated with higher rates of clinical PAD events, and this association was independent of the ABI.

Perspective:

This study reports that the presence of lipid-rich necrotic core in the SFA is associated with a higher rate of clinically important PAD events, measured by a composite outcome of lower extremity amputation, hospitalization for critical limb ischemia, significant ABI decline, and lower extremity revascularization. This association was observed even after excluding lower extremity revascularizations from the composite PAD outcome. Furthermore, associations were independent of potential confounders including PAD severity, measured by the ABI. Additional studies are indicated to determine whether interventions that reduce SFA LRNC may prevent lower extremity events in people with PAD.

Clinical Topics: Cardiac Surgery, Clinical Topic Collection: Dyslipidemia, Invasive Cardiovascular Angiography and Intervention, Noninvasive Imaging, Prevention, Vascular Medicine, Cardiac Surgery and Arrhythmias, Lipid Metabolism, Interventions and Imaging, Interventions and Vascular Medicine, Magnetic Resonance Imaging

Keywords: Amputation, Ankle Brachial Index, Diagnostic Imaging, Femoral Artery, Ischemia, Lipids, Lower Extremity, Magnetic Resonance Imaging, Myocardial Revascularization, Peripheral Arterial Disease, Plaque, Atherosclerotic, Secondary Prevention, Stroke, Vascular Diseases


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