Surgical revascularisation in patients with severe limb ischaemia induces a pro-thrombotic state

Effect of Rivaroxaban and Aspirin in Patients with Peripheral Artery Disease Undergoing Surgical Revascularization: Insights from the VOYAGER PAD Trial

Background: Patients with peripheral artery disease (PAD) requiring lower extremity revascularization (LER) are at high risk of adverse limb and cardiovascular events. VOYAGER PAD demonstrated that rivaroxaban significantly reduced this risk. The efficacy and safety of rivaroxaban has not been described in patients who underwent surgical LER. Methods: The VOYAGER PAD trial randomized patients with PAD after surgical and endovascular LER to rivaroxaban 2.5mg twice daily plus aspirin or matching placebo plus aspirin and followed for a median of 28 months. The primary endpoint was a composite of acute limb ischemia, major vascular amputation, myocardial infarction, ischemic stroke, or cardiovascular death. The principal safety outcome was Thrombolysis in Myocardial Infarction (TIMI) major bleeding. International Society on Thrombosis and Haemostasis (ISTH) bleeding was a secondary safety outcome. All efficacy and safety outcomes were adjudicated by a blinded independent committee. Results: Of the 6564 randomized, 2185 (33%) underwent surgical LER and 4379 (67%) endovascular. Compared to placebo, rivaroxaban reduced the primary endpoint consistently regardless of LER method (p-interaction 0.43). Following surgical LER, the primary efficacy outcome occurred in 199 (18.4%) patients in the rivaroxaban group and 242 (22.0%) patients in the placebo group with a cumulative incidence at 3 years of 19.7% and 23.9%, respectively (HR 0.81, 95% CI 0.67 - 0.98; p=0.026). In the overall trial, TIMI major bleeding and ISTH major bleeding were increased with rivaroxaban. There was no heterogeneity for TIMI major bleeding (p-interaction 0.17) or ISTH major bleeding (p-interaction 0.73) based on LER approach. Following surgical LER, the principal safety outcome occurred in 11 (1.0%) patients in the rivaroxaban group and 13 (1.2%) patients in the placebo group; 3-year cumulative incidence 1.3% and 1.4% respectively (HR 0.88, 95% CI 0.39-1.95; p=0.75) Among surgical patients, the composite of fatal bleeding or intracranial hemorrhage (p=0.95) and postprocedural bleeding requiring intervention (p=0.93) were not significantly increased. Conclusions: The efficacy of rivaroxaban is associated with a benefit in surgical LER patients. While bleeding was increased with rivaroxaban plus aspirin, the incidence was low, with no significant increase in fatal bleeding, intracranial hemorrhage or postprocedural bleeds requiring intervention. Clinical Trial Registration: URL: https://clinicaltrials.gov Unique Identifier: NCT02504216.

Impact of Dual Antiplatelet Therapy after Lower Extremity Revascularization for Chronic Limb Threatening Ischemia (CLTI)

BACKGROUND

The optimal antiplatelet regimen after lower extremity revascularization in patients with chronic limb threatening ischemia (CLTI) is unknown since current recommendations are based on extrapolation of data from trials in coronary artery disease and stroke.

METHODS

We identified all patients undergoing an elective lower extremity revascularization for CLTI in the Vascular Quality Initiative registry discharged on a mono antiplatelet agent (MAPT) or dual antiplatelet therapy (DAPT).

RESULTS

From 2003 to 2018, 50,890 patients underwent revascularization procedures for CLTI, and were discharged on MAPT or DAPT. Of these, 33,781 patients underwent endovascular therapy (EVT) and 17,109 patients underwent open surgery (OS) procedures. The rate of major amputation at 30 days in the target limb in the EVT group was 0.3% and 0.4% in the OS group (P=.22). On Kaplan Meier analyses, patients on MAPT at discharge had a higher risk 1-year major amputation compared to DAPT after EVT but not after OS procedures. Patients on MAPT had lower overall survival and amputation free survival (AFS) at 30 days and 1 year compared to DAPT after both EVT and OS. At 1 year, the MAPT group was at higher risk for target lesion re-intervention after EVT compared to the DAPT group (15.9% vs. 13%, P= .0012). There was no significant difference in thrombosis at 1 year between MAPT and DAPT groups either after EVT (3.9% vs. 3.7%; P = .3048) or OS (3.1% vs. 3.2%; P= .2893). On cox regression analysis, DAPT was associated with improved survival but not major amputation after both EVT and OS.

CONCLUSIONS

In CLTI patients, DAPT at the time of discharge has a positive impact on AFS and overall survival after both EVT and OS as well as target lesion re-intervention after EVT. DAPT was not associated with a positive impact on major amputation after either EVT or OS.

Platelet activation increases in patients undergoing vascular surgery

BACKGROUND

Platelets are a major contributor to atherothrombosis and may contribute to the heightened risk of perioperative cardiovascular events. We sought to examine changes in platelet activity in subjects undergoing vascular surgery.

METHODS

Platelet activity in 18 patients (median age 74, 45% female) undergoing non-emergent open vascular surgery was assessed by light transmission aggregometry in response to saline, epinephrine and adenosine-5 diphosphate (ADP), and by flow cytometric analysis of monocyte-platelet aggregation (MPA). Platelet activity was assessed preoperatively (T1), 1-hour into the operation (T2), 1-hour (T3), 24-hours (T4) and 48-hours post-operatively (T5). Data were compared using the Wilcoxon Signed Ranks Test. Continuous variables are summarized as medians and (interquartile, IQR) ranges.

RESULTS

Spontaneous platelet aggregation increased transiently during the surgical period (T1-5.8% [2.4, 10.8], T2-13.5% [9.3, 26.5], T3-7.5% [3.3, 17], T4-10.0% [7.3, 16.3], T5-7.25% [4.5, 29.9], P=0.002). Similar trends in perioperative platelet activity were noted for platelet aggregation in response to epinephrine (P=0.035) and ADP (P=0.036). Using flow cytometry, we found an increase in MPA during the perioperative period (P=0.047), which was most significant between T1 and T3 (P=0.005).

CONCLUSIONS

Platelet activity increases significantly during and following open vascular surgery. This data may help explain the pathophysiology of increased thrombotic risk during the perioperative period of vascular surgery.

Prospective study on circulating MicroRNAs and risk of myocardial infarction

OBJECTIVES

This study sought to explore the association between baseline levels of microRNAs (miRNAs) (1995) and incident myocardial infarction (1995 to 2005) in the Bruneck cohort and determine their cellular origin.

BACKGROUND

Circulating miRNAs are emerging as potential biomarkers. We previously identified an miRNA signature for type 2 diabetes in the general population.

METHODS

A total of 19 candidate miRNAs were quantified by real-time polymerase chain reactions in 820 participants.

RESULTS

In multivariable Cox regression analysis, 3 miRNAs were consistently and significantly related to incident myocardial infarction: miR-126 showed a positive association (multivariable hazard ratio: 2.69 [95% confidence interval: 1.45 to 5.01], p = 0.002), whereas miR-223 and miR-197 were inversely associated with disease risk (multivariable hazard ratio: 0.47 [95% confidence interval: 0.29 to 0.75], p = 0.002, and 0.56 [95% confidence interval: 0.32 to 0.96], p = 0.036). To determine their cellular origin, healthy volunteers underwent limb ischemia-reperfusion generated by thigh cuff inflation, and plasma miRNA changes were analyzed at baseline, 10 min, 1 h, 5 h, 2 days, and 7 days. Computational analysis using the temporal clustering by affinity propagation algorithm identified 6 distinct miRNA clusters. One cluster included all miRNAs associated with the risk of future myocardial infarction. It was characterized by early (1 h) and sustained activation (7 days) post-ischemia-reperfusion injury and consisted of miRNAs predominantly expressed in platelets.

CONCLUSIONS

In subjects with subsequent myocardial infarction, differential co-expression patterns of circulating miRNAs occur around endothelium-enriched miR-126, with platelets being a major contributor to this miRNA signature.

Fatal basilar artery occlusion under dabigatran occurring 13 days after femoral embolectomy

A male with atrial fibrillation for 30 years underwent embolectomy in his right leg at age 78 years. Postoperatively, he received enoxaparin 60 mg/twice a day (bid), and on day 5, phenprocoumon was started. The patient's son, a general practitioner, changed phenprocoumon to dabigatran 110 mg/bid on day 8. Pain in his left calf induced readmission after 5 days. International normalized ratio was 2.5 and D-dimer was 20 μg/mL. Dabigatran was stopped and dalteparin 5000 International Units/bid and 40 μg alprostadil infusions were started. After 8 hours, he became comatose due to basilar artery occlusion and eventually died. This tragic case raises the issue of postoperative use of dabigatran, a recently introduced thrombin inhibitor.

Effect of Omega-3 fatty acid supplementation on markers of platelet and endothelial function in patients with peripheral arterial disease

OBJECTIVE

Omega-3 fatty acids have been shown to reduce platelet and endothelial activation in patients with or at risk of cardiac disease. We aimed to determine if Omega-3 fatty acid supplementation in addition to best medical therapy can reduce the increased platelet and endothelial activity that is present in patients with intermittent claudication.

METHODS

One hundred and fifty patients who were receiving aspirin and statin therapy were recruited into a randomised cross-over double blind study involving 6 week supplementation with OMACOR fish oil (850-882 mg eicosapentaenoic and docosahexaenoic acid) versus placebo. A 12 week washout period occurred between treatments. Patients with diabetes were excluded. For each outcome a random effects model was fitted in which treatment and period were fixed effects and patients were random effects.

RESULTS

Omega-3 supplementation had no effect on the primary outcome measure von Willebrand factor. Similarly Omega-3 supplementation resulted in no change in unstimulated or stimulated P-selectin expression and fibrinogen binding, or platelet aggregation (Ultegra point of care). Pulse wave velocity was also unchanged. High-sensitivity C-reactive protein, s-ICAM and IL-6 were also unchanged.

CONCLUSION

Supplementation with Omega-3 fatty acids had no affect on platelet and endothelial activation or markers of inflammation in patients with peripheral arterial disease.

Platelet activation, myocardial ischemic events and postoperative non-response to aspirin in patients undergoing major vascular surgery

OBJECTIVES

Myocardial ischemia is the leading cause of postoperative mortality and morbidity in patients undergoing major vascular surgery. Platelets have been implicated in the pathogenesis of acute thrombotic events. We hypothesized that platelet activity is increased following major vascular surgery and that this may predispose patients to myocardial ischemia.

METHODS

Platelet function in 136 patients undergoing elective surgery for subcritical limb ischemia or infrarenal abdominal aortic aneurysm repair was assessed by P-selectin expression and fibrinogen binding with and without adenosine diphosphate (ADP) stimulation, and aggregation mediated by thrombin receptor-activating peptide and arachidonic acid (AA). Cardiac troponin-I (cTnI) was performed.

RESULTS

P-selectin expression increased from days 1 to 3 after surgery [median increase from baseline on day 3: 53% (range: -28% to 212%, P < 0.01) for unstimulated and 12% (range: -9% to 45%, P < 0.01) for stimulated]. Fibrinogen binding increased in the immediate postoperative period [median increase from baseline: 34% (range: -46% to 155%, P < 0.05)] and decreased on postoperative day 3 (P < 0.05). ADP-stimulated fibrinogen binding increased on day1 (P < 0.05) and thereafter decreased. Platelet aggregation increased on days 1-5 (P < 0.05). Twenty-eight (21%) patients had a postoperative elevation (> 0.1 ng mL(-1)) of cTnI. They had significantly increased AA-stimulated platelet aggregation in the immediate postoperative period and on day 2 (P < 0.05), and non-response to aspirin (48% vs. 26%, P = 0.036).

CONCLUSIONS

This study has shown increased platelet activity and the existence of non-response to aspirin following major vascular surgery. Patients with elevated postoperative cTnI had significantly increased AA-mediated platelet aggregation and a higher incidence of non-response to aspirin compared with patients who did not.

Platelet activation increases with the severity of peripheral arterial disease: Implications for clinical management

INTRODUCTION

Patients with peripheral arterial disease (PAD) have increased mortality from cardiovascular events compared with age and sex matched controls Platelets play a major role in atherosclerosis and thrombotic vascular events. Platelet reactivity is increased in patients with PAD compared with healthy controls. We aimed to determine the relationship, if any, between platelet activation and severity of disease.

METHODS AND RESULTS

One hundred eighty-two patients with intermittent claudication (IC) or subcritical limb ischemia (SLI), defined as the presence of rest pain or ulceration, had the following investigations performed: platelet P-selectin expression and bound fibrinogen by flow cytometric analysis and platelet aggregation using the rapid platelet function assay with arachidonic acid (AA) and thrombin receptor activation peptide (TRAP) as agonists. Patients with SLI compared with IC had significantly enhanced ADP stimulated P-selectin expression (median 42.45% [inter-quartile range 33.32% to 58.5%] vs 35.2% [26.07% to 46.32%], P = .002) and bound fibrinogen (73.7% [54.3% to 83.2%] vs 63.7% [43.8% to 76.5%], P = .001). TRAP stimulated aggregation was higher (207 [153 to 238] PAU vs 183[155 to 199] PAU, P = .04) but AA mediated aggregation was not significantly different. An ankle-brachial pressure index (ABPI) of less than 0.6 was associated with increased ADP stimulated P-selectin and bound fibrinogen (P < .05). ABPI correlated inversely with ADP stimulated P-selectin expression (r = -0.228, P = .003), ADP stimulated fibrinogen binding (r = -0.156, P = .043) and TRAP stimulated aggregation (r = -0.179, P = .04).

CONCLUSION

We have demonstrated for the first time that progression of severity of PAD is not only reflected by symptoms, signs, and ABPI but also by increased platelet activity as assessed by both flow cytometry and aggregation. As patients with more severe PAD have increased cardiovascular mortality, our findings suggest that new strategies for platelet inhibitory therapy are indicated in these patients.