Established peripheral artery disease (PAD) is a significant risk factor for patients with comorbid acute myocardial infarction (AMI) and cardiogenic shock (CS), according to a new widescale registry analysis. The findings from 71,690 Medicare beneficiaries were published Monday online ahead of the April 5 issue of the Journal of the American College of Cardiology, with authors led by Nino Mihatov, MD, from Columbia University Irving Medical Center/New York-Presbyterian Hospital, Beth Israel Deaconess Medical Center and Harvard Medical School. In coronary artery disease (CAD) patients presenting with AMI, CS remains the leading cause of death, the researchers noted, with in-hospital mortality estimated as high as 50%. This is despite advances in revascularization strategies and mechanical circulatory support (MSC) devices. Over 40% of CAD patients also have comorbid lower-extremity PAD, they added, leading to even greater cardiovascular event and overall mortality rates, they added. It is known that for CAD patients who also have PAD, critical revascularization strategies and outcomes are significantly influenced. “This may be related to access site issues, atherosclerotic burden in coronary arteries and other vital organs (eg, carotid, renal arteries), and high-risk comorbid illnesses related to the development of PAD,” the researchers said. However, the relationship between PAD and clinical outcomes following AMI complicated by CS remains poorly characterized, the authors said. They added that despite the fact MCS is now used in upwards of one-third of CS patients, the utilization of MCS devices among CS patients with PAD and the rates of associated outcomes is unknown. The current study’s aim was, therefore, to clarify the association between lower-extremity PAD and outcomes after AMI and CS, and to determine how MCS is being used in this population versus similar patients without PAD. It included all fee-for-service beneficiaries aged 65 years or older on the U.S. state-backed insurance system, Medicare, who were hospitalized at short-term acute-care hospitals across the States from October 1, 2015, to June 30, 2018. The patients had a principal diagnosis of AMI and a secondary diagnosis of CS based on the International Classification of Diseases (ICD), and all those with a presentation for CS associated with AMI in the year preceding the index hospitalization were excluded. Patients with established PAD were identified using the relevant ICD claim codes (ICD-9-CM or ICD-10-CM) in the year preceding the date of the index CS/AMI admission. Of the 71,690 patients included, 5.9% (4,259) had PAD. Their mean age was 77.8 ± 7.9 years, 58.7% were male, and 84.3% were white. The primary outcome measure, measured through Dec. 31, 2018, included in-hospital mortality, which overall was 47.2% – a rate significantly higher in those with PAD (56.3% vs. 46.6% without PAD; adjusted odds ratio [OR]: 1.50; 95% confidence interval [CI]: 1.40-1.59; P < 0.001). Out-of-hospital mortality, the other primary endpoint, was also greater in those with PAD (67.9% vs. 40.7%; adjusted hazard ratio [HR]: 1.78; 95% CI: 1.67-1.90; P < 0.0001). PAD patients also experienced higher rates of in-hospital amputation (1.6% vs. 0.2%; P < 0.001), major bleeding (2.2% vs. 1.4%; P < 0.001) and lower extremity revascularization (4.1% vs. 1.9%; P < 0.001). The researchers found that MCS was also used less frequently in PAD patients, at a rate of 21.5% vs. 38.6% of those without PAD (P < 0.001). “Findings were consistent in patients who underwent coronary revascularization,” said the researchers. “These findings highlight the importance of identifying and considering PAD as a risk factor and underscores the need for a multidisciplinary approach to managing these patients,” they added. The researchers went on to call for further studies to evaluate strategies that can reduce the risk of adverse limb events and improve clinical outcomes in these AMI and CS patients with PAD. In an accompanying editorial, Mehdi H. Shishehbor, DO, MPH, PhD, and Yulanka Castro-Dominguez, MD, from the Harrington Heart and Vascular Institute, University Hospitals, and Case Western Reserve University, Cleveland, highlighted a “major limitation” of the study: establishing the causality between PAD and the findings of poor outcomes. “Is it possible that patients with PAD had less revascularization and worse outcomes because of more advanced atherosclerotic and comorbid disease?” they asked. “Furthermore, having used only a Medicare fee-for-service population, its findings can be extrapolated only to older patients who may be less likely to be treated aggressively, either with revascularization or MCS, given advanced severe illness, multiple comorbidities, or patient preferences.” Nevertheless, they concurred that understanding the effect of PAD on a patient’s risk profile is “crucial to be able to deliver the most appropriate therapies and specialized management.” “Only with an interdisciplinary approach using expertise across different disciplines will we be able to reduce morbidity and mortality in this high-risk population with PAD.” Sources: Mihatov N, Mosarla RC, Kirtane AJ, et al. Outcomes Associated With Peripheral Artery Disease in Myocardial Infarction With Cardiogenic Shock. J Am Coll Cardiol 2022;79:1223-1235. Shishehbor MH, Castro-Dominguez Y. Peripheral Artery Disease: The New and Old Silent Killer. J Am Coll Cardiol 2022;79:1236-1238. Image Credit: Africa Studio – stock.adobe.com