Association of PeriOPerative Aspirin-ResisTance and CardioVascular Outcome

The aim of our study is to investigate the association between perioperative aspirin resistance and Myocardial Injury after Non-cardiac Surgery (MINS) in patients undergoing vascular surgery.

Because of new surgical techniques, advanced monitoring modalities and improvements in perioperative care, perioperative mortality and morbidity have been significantly reduced in the last decades; however, patients still suffer from high perioperative mortality and morbidity, especially those with pre-existing cardiovascular diseases. Not only perioperative myocardial infarction but also myocardial injury after non-cardiac surgery, which presents without clinical symptoms, is associated with an adverse outcome. Possibilities to preoperatively identify patients at cardiovascular risk are limited and prophylactic interventions are not yet established or controversial.

Aspirin is used for primary and secondary prevention in cardiovascular diseases. New-onset increased platelet function on aspirin treatment (aspirin resistance) has been demonstrated in cardiac and vascular surgery. Yet, it has not been investigated whether a new perioperative aspirin resistance is associated with higher risk of myocardial injury after non-cardiac surgery (MINS) and cardiovascular events.

The aim of this study is to evaluate a potential association between new-onset aspirin resistance and MINS in patients undergoing vascular surgery. If there is an association of perioperative aspirin resistance and MINS during vascular surgery, the detection of perioperative aspirin resistance could be used as perioperative risk stratification tool in order to improve clinical risk stratification and reduce perioperative morbidity and mortality.

Therefore, 220 patients treated with aspirin and scheduled for vascular surgery will be recruited. Blood will be drawn at predefined time points before surgery and up to three days postoperatively. Aspirin resistance will be measured by Multiplate Analyzer prior to surgery, one hour after skin-incision, four hours after surgery and on post-OP days one and two. Adverse cardiovascular events will be recorded until 30 days post-OP. ECGs will be recorded preoperatively and on post-OP day 3. High-sensitive cardiac Troponin T will be measured prior to surgery and on post-OP days one to three. Patient charts will be screened and a telephone interview will be performed to detect cardiovascular events after discharge until post-OP day 30.

Eligibility Criteria:
Inclusion Criteria:

* 18 years or older
* Preoperative aspirin treatment at least 14 days prior to surgery
* Elective vascular surgery
* In-patient treatment
* Informed consent

Exclusion Criteria:

* 17 years of age or younger
* Known pregnancy or breastfeeding
* Missing informed consent
* Ambulatory or day-case surgery
* Emergency surgery
* Current clopidogrel or non-steroidal anti-inflammatory drug treatment
* Preoperative aspirin resistance
* Current thrombocytopenia (\<100000 platelet/µl)
* Liver or renal failure (GOT/GPT and/or creatinine increased \>2-fold)
* Entity which is part of the composite endpoint diagnosed within past 28 days
* Angiography without surgical intervention