Evaluation of Platelet Aggregability in Patients With Previous Acute Myocardial Infarction or Concomitant Lower Extremity Peripheral Artery Disease

After an episode of acute ischemic syndrome, patients with concomitant peripheral arterial disease have a worse short- and long-term prognosis compared to patients with isolated coronary disease, but the mechanisms responsible are poorly understood. In this population, the presence of high platelet aggregability despite the use of antiplatelet drugs is related to a greater risk of future complications, including heart attack and death from all causes.

Thus, the main objective of the present project is to evaluate the role of platelet aggregability, analyzed by optical aggregometry using the AggRAM® equipment, in patients with a history of previous acute myocardial infarction with and without the presence of peripheral arterial disease. Among the secondary objectives, it is worth analyzing platelet aggregability, in both groups, using the Plateletworks® method. This is a case-control study, with groups differentiated by the presence or absence of peripheral arterial disease, matched by sex and age.

It is expected that, in the end, relevant aspects related to platelet aggregation will be better characterized in this high cardiovascular risk population, with a likely impact on new therapeutic strategies that can positively influence the morbidity and mortality of these patients.

Polyvascular involvement is frequently present in atherosclerotic disease (AD). Lower Extremity Peripheral Artery Disease (PAD) represents one of the manifestations of AD; it is estimated that around 47% of people with atherosclerotic disease have involvement in more than one vascular bed, with coronary atherosclerotic disease and lower limb AD being the most prevalent.

Initial studies suggest that platelet aggregability is increased in patients with PAD and the level of platelet aggregability is associated with the severity of PAD.However, to our knowledge, there are no studies in the literature analyzing platelet aggregability in patients with previous AMI with and without the concomitant presence of PAD, which is the proposal of this research project.

This study is an observational, case-control study, matched by sex and age. Two groups will be selected: Patients with previous infarction and isolated coronary involvement (Group 1); Patients with previous AMI and concomitant presence of PAD of the lower limbs (Group 2).

Primary objective is compare platelet aggregability analyzed by optical aggregometry-ADP (AggRAM™- Helena Laboratories) between the groups. Secondary objetives includes laboratorial test of inflammation, coagulation and subgroup analysis.

Eligibility Criteria:
Inclusion Criteria:

1. Men and women aged ≥ 18 years;
2. Daily use of AAS 81-100 mg and statins;
3. History of acute myocardial infarction, proven by medical record analysis;
4. Group 2 (patients with PAD): Ankle-Brachial Index number (ABI) ≤ 0.9 in at least one of the lower limbs. In diabetic patients with ABI \> 1.4, the Hallux-Brachialis Index should be performed if possible; if the patient presents a value \< 0.7, they can be included;
5. Signing of the Free and Informed Consent Form.

Exclusion Criteria:

1. Use of adenosine-diphosphate (ADP) receptor antagonists in the last 7 days before inclusion in the study;
2. Use of Anticoagulants in the last 30 days before inclusion in the study;
3. Clopidogrel allergy;
4. Known atherosclerotic carotid disease or carotid bruit;
5. History of upper gastrointestinal bleeding in the last 12 months;
6. Pregnancy or lactation;
7. Known platelet dysfunction or platelet count \<100,000/µL or \>450,000/µL;
8. Known liver disease or coagulation disorder;
9. Hematocrit less than 34% or greater than 55%