Wennberg, Paul W.

Summary: Background: Peripheral artery disease (PAD) is a risk factor for adverse limb events (LE) and cardiovascular events (CVE) that coexists with type 1 (T1) and 2 (T2) diabetes mellitus (DM). Little is known about comparative risk of LE and CVE in T1/T2 DM patients with PAD. Patients and methods: We queried our database of 40,144 patients ≥18 years old who underwent ankle brachial index (ABI) measurement from 01/1996-02/2020. We isolated T1/T2 DM patients with PAD diagnosed by ankle brachial index (ABI; low [<1.0] or elevated [>1.4]) and retrieved demographics including glycated hemoglobin (HbA1c). Primary outcomes were LE (critical limb ischemia/vascular amputation) and CVE (myocardial infarction/ischemic stroke). All-cause mortality was a secondary outcome. Multivariable Cox proportional regression yielded hazard ratios (HR) with 95% confidence intervals (CI) after adjusting for pertinent risk factors including age, hypertension, hyperlipidemia, smoking, and HbA1c. Results: Our study found 10,156 patients with PAD and DM (34% T1DM, 66% T2DM) with median follow-up time 34 mo (IQR 85 mo). T1DM patients were younger than T2DM (mean age 67 vs. 70 years), with higher median HbA1c (7.7 [IQR 1.9] vs. 6.7% [IQR 1.6]), and more prevalent hypertension, hyperlipidemia, CAD, and CKD. Antiplatelet and statin use was equivocal. Elevated ABI was more common in T1DM (47 vs. 28%). LE occurred in 23% and CVE in 12% patients. LE risk was higher in T1 than T2 DM patients (HR 1.58 [95% CI 1.44, 1.73], p<0.0001), but CVE and all-cause mortality were equivocal. These observations were preserved across ABI and HbA1c subgroup analyses. Conclusions: PAD patients with T1DM had a higher LE risk than those with T2DM, even after adjustment for glycemic control and pertinent risk factors, but CVE risk and all-cause mortality were equivocal. These data suggest a potential role for more intensive LE risk modification in PAD patients with T1DM, but further investigation is needed.

Introduction: Peripheral artery disease (PAD) is a risk factor for adverse limb events (LE) and cardiovascular events (CVE) that often coexists with type 1 (T1) and type 2 (T2) diabetes mellitus (DM), which differ mechanistically. There is a paucity of data on comparative risk of LE and CVE in T1DM and T2DM patients with PAD. Methods: We queried our database of 40,144 patients ≥18y old who underwent ankle brachial index (ABI) measurement from 01/1996-02/2020. We isolated patients with T1DM or T2DM and with PAD diagnosed by ABI (low [<1.0] or elevated [>1.4]). We retrieved demographics including hemoglobin A1c (A1c). Primary outcomes were LE (critical limb ischemia or vascular amputation) and CVE (myocardial infarction or ischemic stroke). All-cause mortality was a secondary outcome. Multivariable Cox proportional regression yielded hazard ratios (HR) with 95% confidence intervals (CI) after adjusting for age, sex, A1c, hypertension, hyperlipidemia, coronary artery disease (CAD), chronic kidney disease (CKD), and tobacco use. Results: Our study found 9,271 patients with PAD and DM (36% T1DM, 64% T2DM) with median follow-up time 34 mo (interquartile range [IQR] 85 mo). T1DM patients were younger than T2DM (mean age 67 vs 70y), with higher median A1c (7.7 [IQR 1.9] vs 6.7% [IQR 1.6]), and higher prevalence of hypertension, hyperlipidemia, CAD, and CKD. Antiplatelet and statin use did not differ. Elevated ABI was more common in T1DM (47 vs 27%). LE occurred in 23% and CVE in 12% of patients. LE risk was higher in T1DM patients than T2DM (HR 1.59[95% CI 1.45,1.74], p<0.0001), but CVE and all-cause mortality did not differ significantly. Conclusions: PAD patients with T1DM had a higher LE risk than those with T2DM, even after adjustment for A1c and pertinent risk factors, but CVE risk and all-cause mortality were equivocal. These data suggest a potential role for more intensive LE risk modification in PAD patients with T1DM, but further investigation is needed to minimize limb morbidity.

Summary: Background: Peripheral artery disease (PAD) impacts 3–12% of patients worldwide and is characterized by endothelial dysfunction and inflammatory pathways which are also common to venous thromboembolism (VTE), but there is a paucity of evidence regarding VTE risk in PAD patients. We investigated whether PAD is an independent risk factor for VTE. Patients and methods: We reviewed medical records of patients undergoing ABI studies at Mayo Clinic from 01/1996-02/2020. We classified patients by ABI (low [<1.0], normal [1.0–1.4], or elevated [>1.4]), as well as by specific low ABI subgroup: severely reduced (ABI: 0.00–0.39), moderately reduced (0.40–0.69), mildly reduced (0.70–0.90), and borderline reduced (0.91–0.99). The primary outcome was incident VTE event (acute lower extremity deep vein thrombosis or pulmonary embolism) after ABI measurement. Multivariable Cox proportional regression was used to calculate hazard ratios (HR) with 95% confidence intervals (CI) after adjusting for age, sex, active smoking, cancer, previous VTE, thrombophilia, anticoagulation, and revascularization. Results: 39,834 unique patients (mean age 66.3±14.3 years, median follow-up 34 months) were identified. 2,305 VTE events occurred in patients without PAD (13.0%), 2,218 in low ABI patients (13.0%), and 751 in elevated ABI patients (14.8%). After risk factor adjustment, VTE risk was modestly increased for PAD overall (HR: 1.12, 95% CI [1.06, 1.18]), including low ABI (HR: 1.11, 95% CI [1.04, 1.18]) and elevated ABI groups (HR: 1.15, 95% CI [1.04, 1.26]), compared to patients without PAD. The greatest VTE risk was in severely low ABI patients (HR: 1.46, 95% CI [1.31, 1.64]). Conclusions: In a large longitudinal cohort, we present strong clinical evidence of PAD, with low and elevated ABI, as an independent VTE risk factor, with the highest risk seen in patients with severely low ABI. Continued research is required to further investigate this relationship and its intersection with functional performance status to optimize VTE risk reduction or anticoagulation strategies in the PAD population.

Background: Patients with peripheral artery disease (PAD) are at increased risk for major adverse limb and cardiac events including mortality. Developing screening tools capable of accurate PAD identification is a necessary first step for strategies of adverse outcome prevention. This study aimed to determine whether machine analysis of a resting Doppler waveform using deep neural networks can accurately identify patients with PAD. Methods: Consecutive patients (4/8/2015 – 12/31/2020) undergoing rest and postexercise ankle–brachial index (ABI) testing were included. Patients were randomly allocated to training, validation, and testing subsets (70%/15%/15%). Deep neural networks were trained on resting posterior tibial arterial Doppler waveforms to predict normal (> 0.9) or PAD (⩽ 0.9) using rest and postexercise ABI. A separate dataset of 151 patients who underwent testing during a period after the model had been created and validated (1/1/2021 – 3/31/2021) was used for secondary validation. Area under the receiver operating characteristic curves (AUC) were constructed to evaluate test performance. Results: Among 11,748 total patients, 3432 patients met study criteria: 1941 with PAD (mean age 69 ± 12 years) and 1491 without PAD (64 ± 14 years). The predictive model with highest performance identified PAD with an AUC 0.94 (CI = 0.92–0.96), sensitivity 0.83, specificity 0.88, accuracy 0.85, and positive predictive value (PPV) 0.90. Results were similar for the validation dataset: AUC 0.94 (CI = 0.91–0.98), sensitivity 0.91, specificity 0.85, accuracy 0.89, and PPV 0.89 (postexercise ABI comparison). Conclusion: An artificial intelligence-enabled analysis of a resting Doppler arterial waveform permits identification of PAD at a clinically relevant performance level.

Introduction: Patients with concomitant peripheral artery disease (PAD) and heart failure (HF) are known to have increased morbidity and mortality. Though they share common risk factors, the utility of HF screening in patients with PAD remains controversial and without international consensus. We sought to clarify whether PAD is an independent risk factor for HF. Methods: We performed a retrospective analysis of adult patients without a history of heart failure who underwent ankle brachial index (ABI) measurement for any indication between 1995-2020. Patients were then stratified by ABI: PAD with low ABI (<1.10), healthy (ABI= 1.10-1.39), and PAD with elevated ABI (>1.39). The associations between PAD and incident diagnosis of heart failure, systolic dysfunction (HF with reduced ejection fraction, HFrEF), and diastolic dysfunction (HF with preserved ejection fraction, HFpEF) were assessed. All patient and outcomes variables were obtained using the institutional electronic health record. Multivariable Cox proportional regression was used to calculate hazard ratios (HR) with 95% confidence intervals (CI) after adjusting for age, sex, hypertension, diabetes, and active tobacco use. Results: The cohort included 36,816 patients (median follow-up 4.21 years), of whom 2,116 (5.7%) were diagnosed with HF. Among HF patients, 1,110 (3.0%) had HFrEF and 1,006 (2.7%) had HFpEF. Both low and elevated ABI groups were associated with an increased risk of HF, both HFrEF, and HFpEF. After multivariable analysis, PAD with elevated ABI was associated with higher overall HF risk (HR, 2.36 [95% CI, 2.03, 2.73]) than low ABI (HR, 1.56 [95% CI, 1.40, 1.74]) when compared to normal ABI. Similarly, PAD with elevated ABI was associated with greater risk of HFrEF (HR, 2.37 [95% CI, 1.93, 2.92]) and HFpEF (HR, 1.82 [95% CI, 1.48, 2.25]) than PAD with low ABI (HFrEF: HR 1.77 [95% CI, 1.52, 2.07], HFpEF: HR 1.31 [95% CI, 1.12, 1.52]). Conclusions: PAD, especially with elevated ABI, is an independent risk factor for heart failure even after adjusting for common HF risk factors. Our findings support HF screening in PAD patients, but longitudinal data on HF morbidity and mortality is necessary to evaluate the value of this practice.

Introduction: Peripheral arterial disease (PAD) increases cardiovascular (CV) morbidity and mortality, but remains underdiagnosed and undertreated. Several trials support low-dose rivaroxaban in PAD treatment, although this has yet to be widely adopted in clinical practice. The effect of warfarin and direct oral anticoagulants (DOACs) on comprehensive PAD outcomes warrants further study. Hypothesis: Anticoagulant therapy, particularly DOACs, improves CV outcomes in PAD. Methods: We conducted a retrospective study of patients who underwent ankle-brachial index testing (ABI) from 1996 – 2020 at Mayo Clinic. We included patients with PAD defined by abnormal ABI (<1.0 or >/=1.4). Prolonged (>6 months) DOAC or warfarin use was compared to no anticoagulant therapy. Multivariable (MV) regression, controlling for baseline CV risk factors, was used. Results: 21,891 patients had abnormal ABI readings; 3,093 were on warfarin and 267 were on DOAC for any indication. Anticoagulation improved mortality, with DOACs superior to warfarin. DOACs improved critical limb ischemia (CLI)/amputation in univariate analysis, although this was not significant in MV. Patients with poorly compressible vessels (ABI >/=1.4) had increased limb outcomes compared to reduced ABI (<1.0). Ischemic stroke and myocardial infarction occurred more frequently in those on anticoagulation, but the risk was less for DOACs vs. warfarin. Notably, both anticoagulant groups had greater baseline comorbidity than the non-anticoagulant group; the DOAC and warfarin groups were similar. Major bleeding (6.7%) was increased in both anticoagulant groups, but less so with DOACs and this was similar to the bleeding risk seen with aspirin (HR 1.20). Conclusion: Anticoagulant therapy improved mortality in a large cohort of PAD patients. The risk of limb events appears improved in those on DOACs. DOACs showed improved risk profiles compared to warfarin regarding CV and bleeding outcomes.

Introduction: Peripheral arterial disease (PAD) is a strong predictor of systemic atherosclerosis with substantial morbidity and mortality. Medical management in PAD and coronary artery disease (CAD) has changed in recent eras with the use of high intensity statin and dual antiplatelet therapies. Hypothesis: Test whether mortality and major adverse cardiovascular events (MACE) (death and MI) has decreased over eras among PAD patients undergoning revascularization with percutaneous coronary intervention (PCI). Methods: Longitudinal cohort study of 549 patients who underwent PCI and non-invasive lower arterial study between 1997 and 2008 as identified in the Mayo Clinic PCI registry were stratified into 2 time eras: 1997-2003 (era1), and 2004-2008 (era2). PAD was assessed using the highest resting ABI and stratified according to established categories; < 0.90 (definite PAD); 1.00-1.39 (normal); and ≥ 1.40 defined a non-compressible artery. Kaplan-Meier methods were used to analyze follow-up survival. Results: Stratified by ABI over both time eras, 225 patients had PAD, 94 were non-compressible, and 142 were normal. Overall mortality rates were higher in era2 non-compressible and PAD patients than in non-PAD patients when compared to era1 (58%, 33%, 26%, vs 49% 32%, 19%, p<0.001 for all within-era comparisons) (Figure 1). MACE-free survival were higher in era2 non-compressible and PAD patients than in non-PAD patients when compared to the era1 (64%, 41%, 29% vs 59% 39%, 25%, p≤0.005 for all within-era comparisons). There were significant differences in medical therapy between era2 vs. era1 with higher discharge use of aspirin (98%; 94%), beta-blockers (88%; 66%), any lipid lowering drugs (86%; 76%), ACE inhibitors (67%; 56%), and diuretics (52%; 40%). Conclusions: Over the past two eras, the overall mortality has increased among patients with PAD and non-compressible vessels in era2 vs. era1 despite higher utilization of statin and antiplatelet therapies.

Abstract Context Peripheral artery disease (PAD) is highly prevalent in the general population, affecting up to 25% of patients 55 years of age or older. There is a known association with acute ischemic stroke, but limited large cohort studies exist pertaining to the relationship between PAD severity and incident ischemic stroke. Objectives To evaluate the risk of incident ischemic stroke and mortality along the spectrum of low and elevated ankle brachial index (ABI) measurement. Methods We performed a retrospective extraction of ABI data of all adult patients who underwent lower extremity physiology study for any indication from January 1, 1996 to June 30, 2018 in the Mayo Clinic health system. PAD was categorized into severe, moderate, mild, and borderline based on ABI measurements and poorly compressible arteries (PCA). These were compared with normal ABI measurements. Associations of PAD/PCA with new ischemic stroke events and all cause mortality were analyzed. Hazard ratios (HR) were calculated using multivariable Cox proportional regression with 95% confidence intervals. Results A total of 39,834 unique patients were included with a median follow up duration of 4.59 years. All abnormal ABI groups, except borderline PAD, were associated with increased risk of incident ischemic stroke after multivariate regression compared to normal ABI. A severity-dependent association was observed between PAD and ischemic stroke with moderate (HR, 1.22 [95% CI, 1.10–1.35]) and severe (HR, 1.19 [95% CI, 1.02–1.40]) categories conferring similar risk in comparison to normal ABI. Patients with PCA carried the greatest ischemic stroke risk (HR, 1.30 [95% CI, 1.15–1.46]). Similarly, abnormal ABI groups were associated with a significant risk for all cause mortality in a severity-dependent manner, with severe PAD conferring the greatest risk (HR, 3.07 [95% CI, 2.88–3.27]). Conclusions This study adds to the growing body of evidence that both PAD and PCA are independent risk factors for incident ischemic stroke and all cause mortality. The association of PAD severity and PCA with risk of ischemic stroke may help clinicians with risk stratification and determining treatment intensity.

Abstract The calf muscle pump is a major determinate of venous return in the legs but has not been studied as a risk factor for venous thromboembolism (VTE). A population-based cohort study of Olmsted County, Minnesota residents was performed using calf pump function (CPF) measurements from venous plethysmography studies from 1998 to 2015. Patients with a history of VTE were excluded. Nursing validated VTE outcomes from the Rochester Epidemiology Project were identified after the index study date, and patients with reduced CPF (rCPF) were compared with patients with normal CPF. A total of 1532 patients with recorded CPF (28% air and 72% strain gauge plethysmography) were included; 591 (38.5%) had normal CPF, 353 (23.0%) had unilateral rCPF, and 588 (38.3%) had bilateral rCPF. Any VTE occurred in 87 patients (5.7%) after a median follow-up of 11.7 years (range, 0-22.0 years). Comparing patients with bilateral reduced to bilateral normal CPF, the unadjusted hazard ratio (HR) for incident VTE was 2.0 (95% confidence interval [CI], 1.2-3.4) and after adjusting for age, BMI, and Charlson Comorbidity Index, the HR was 1.68 (95% CI, 0.98-2.89). The adjusted HR for ipsilateral deep vein thrombosis was evaluated in 3064 legs comparing legs with reduced to normal CPF and was 1.71 (95% CI, 1.03-2.84). Mortality was significantly higher in both the bilateral (P &lt; .001) and unilateral (P &lt; .001) rCPF groups compared with normal CPF. Our results demonstrate that CPF is a risk factor for VTE in an otherwise low-risk ambulatory population and might be a useful component in risk stratification models.