PAD Significantly Ups Morbidity and Mortality in AMICS

The treatment of patients with acute MI complicated by cardiogenic shock (AMICS) requires swift action, but a new study suggests that those who also have PAD bring additional challenges that need to be addressed early to improve procedural and survival odds.

“Peripheral artery disease really is a glaring and important comorbidity that needs greater attention,” said senior study author Eric A. Secemsky, MD, MSc (Beth Israel Deaconess Medical Center, Boston, MA). “We found that even with a very stringent definition of symptomatic PAD, these patients are treated differently and have grave prognoses.”

Patients with both AMICS and PAD were less likely than those without PAD to receive mechanical circulatory support (MCS), and even when they did, they were more likely to die than those without PAD receiving MCS (51.9% vs 41.0%; P < 0.001). The PAD group also had significantly higher risks of out-of-hospital mortality and adverse limb outcomes.

In an accompanying editorial, Mehdi H. Shishehbor, DO, MPH, PhD, and Yulanka Castro-Dominguez, MD (both Case Western Reserve University, Cleveland, OH), say understanding how comorbid PAD alters risk profiles is crucial to ensuring that those patients receive specialized management and appropriate therapies.

“Early integration of vascular specialists who can help assess the degree of PAD severity, and inform potential strategies or interventions that could facilitate revascularization or MCS initiation, as well as reduce the risk of limb loss, is crucial,” they write. Training of interventional cardiologists in proper vascular assessment, safe techniques for large-bore access and closure, and recognition and management of access-related complications will help improve care in PAD patients requiring complex interventions, Shishehbor and Castro-Dominguez say, adding that technical advances like external antegrade perfusion and  alternative access sites will provide additional management options.  

Higher In- and Out-of-Hospital Risks

The analysis, which was led by Nino Mihatov, MD (NewYork-Presbyterian/Columbia University Irving Medical Center, NY), and published in the Journal of the American College of Cardiology, included 71,690 Medicare patients hospitalized with AMICS. Among them, approximately 6% also had a prior diagnosis of PAD. Revascularization was less frequent in those with PAD than without PAD for both PCI (27.3% vs 42.7%) and CABG (6.6% vs 13.2%). Similarly, use of MCS occurred in 21.5% of PAD patients versus 38.6% of those without PAD (P < 0.001 for all comparisons).

Rates of in-hospital mortality were higher in those with versus without PAD (56.3% vs 46.6%), as were rates of major bleeding (2.2% vs 1.4%), in-hospital amputation (1.6% vs 0.2%), and lower-extremity revascularization (4.1% vs 1.9%; P < 0.001 for all). There were no differences in rates of cerebrovascular events or cardiac arrest between the PAD and non-PAD groups. Multivariable adjustment confirmed a 1.4-fold higher rate of in-hospital death, sevenfold higher risk of amputation, 1.4-fold increased risk of bleeding, and 2.2-fold higher risk of lower-extremity revascularization in the PAD group.

In terms of out-of-hospital outcomes, the PAD group again had greater risks of long-term death (HR 2.11; 95% CI 1.98-2.24), acute MI (HR 1.22; 95% CI 1.03-1.44), hear failure (HR 1.50; 95% CI 1.36-1.65), and hospital readmission (HR 1.33; 95% CI 1.25-1.41) than those without PAD. After multivariable adjustment, PAD continued to be associated with increased long-term death and hospital readmission.

Approximately 38% of the study population received MCS (intra-aortic balloon pump in 18.6%, extracorporeal membrane oxygenation in 12.1%, and percutaneous ventricular assist device in 6.9%). The percentage with PAD who received this treatment was 21.5%, versus 38.6% of non-PAD patients (P < 0.001). In multivariable adjustment, PAD patients who received MCS had a 1.5-fold higher risk of death, a 4.4-fold higher risk of amputation, and 2.3-fold higher risk of in-hospital lower-extremity revascularization compared with patients without PAD who received MCS.

The out-of-hospital outcomes in the MCS groups also were increased after multivariable adjustment in those with versus without PAD for death (HR 1.60; 95% CI 1.40-1.93), heart failure (HR 1.50; 95% CI 1.25-1.80), and readmission (HR 1.26; 95% CI 1.12-1.43).

Analysis according to revascularization type revealed that PAD patients who underwent PCI had greater risks of in-hospital death, amputation, and need for lower-extremity revascularization than those without PAD. In those with PAD who underwent CABG, in-hospital death was higher in the PAD versus no-PAD group (P = 0.04).

Emphasis on Multidisciplinary Approach

“I think a lot of people may see these data and say [they’re not surprised] that this is the case with PAD patients, but the question is, does it need to be the case and can we do better?” Secemsky noted. “We need to be thinking about these patients differently and a bit more thoughtfully than we do when we put someone in a typical mixed-shock algorithm. We know from the data that these PAD patients are going to do worse and we should be pulling these out and making selected algorithms for those who have known significant lower-extremity PAD that can result in limb-threatening disease.”

Shishehbor and Castro-Dominguez note that less-aggressive treatment in the study population may have been related to their older age. A major limitation of the study, they add, is establishing causality between PAD and poor outcomes, since more advanced atherosclerotic and comorbid disease cannot be ruled out. Furthermore, the PAD group had more atrial fibrillation, chronic kidney disease, chronic obstructive pulmonary disease, hear failure, and diabetes, raising the possibility that a “conglomerate of these factors” may have impacted decisions about revascularization as well as outcomes.

To TCTMD, Secemsky said the findings add weight to the importance of multidisciplinary shock team assessment.

“I think it comes down to harmonizing these teams and trying to make sure that there's a multifaceted . . . group of specialists when PAD is a known comorbidity of the patient,” he said.