Primary prevention of ischaemic cardiovascular disorders with antiplatelet agents

Bioactive peptides and proteins as alternative antiplatelet drugs

Antiplatelet drugs reduce the risks associated with atherothrombotic events and show various applications in diverse cardiovascular diseases including myocardial infarctions. Efficacy of the current antiplatelet medicines including aspirin, clopidogrel, prasugrel and ticagrelor, and the glycoprotein IIb/IIIa antagonists, are limited due to their increased risks of bleeding, and antiplatelet drug resistance. Hence, it is important to develop new effective antiplatelet drugs, with fewer side-effects. The vast repertoire of natural peptides can be explored towards this goal. Proteins and peptides derived from snake venoms and plants represent exciting candidates for the development of novel and potent antiplatelet agents. Consequently, this review discusses multiple peptides that have displayed antiplatelet aggregation activity in preclinical drug development stages. This review also describes the antiplatelet mechanisms of the peptides, emphasizing the signaling pathways intervened by them. Also, the hurdles encountered during the development of peptides into antiplatelet drugs have been listed. Finally, hitherto unexplored peptides with the potential to prevent platelet aggregation are explored.

Platelets, inflammation and anti-inflammatory effects of antiplatelet drugs in ACS and CAD

Platelets play a pivotal role in chronic inflammation leading to progression of atherosclerosis and acute coronary events. Recent discoveries on novel mechanisms and platelet-dependent inflammatory targets underpin the role of platelets to maintain a chronic inflammatory condition in cardiovascular disease. There is strong and clinically relevant crosslink between chronic inflammation and platelet activation. Antiplatelet therapy is a cornerstone in the prevention and treatment of acute cardiovascular events. The benefit of antiplatelet agents has mainly been attributed to their direct anti-aggregatory impact. Some anti-inflammatory off-target effects have also been described. However, it is unclear whether these effects are secondary due to inhibition of platelet activation or are caused by direct distinct mechanisms interfering with inflammatory pathways. This article will highlight novel platelet associated targets that contribute to inflammation in cardiovascular disease and elucidate mechanisms by which currently available antiplatelet agents evolve anti-inflammatory capacities, in particular by carving out the differential mechanisms directly or indirectly affecting platelet mediated inflammation. It will further illustrate the prognostic impact of antiplatelet therapies by reducing inflammatory marker release in recent cardiovascular trials.

Benefit-Risk Assessment of Fish Oil in Preventing Cardiovascular Disease

Cardiovascular disease (CVD) is a preventable disease, which combines two general processes: chronic vascular inflammation and acute thrombosis. Both are amplified with positive feedback signals by n-6 eicosanoids derived from food-based n-6 highly unsaturated fatty acids (n-6 HUFA). This amplification is lessened by competing actions of n-3 HUFA. Death results from fatal interactions of the vascular wall with platelets and clotting proteins. The benefits of fish oil interventions are confounded by complex details in pharmacokinetics, pharmacodynamics, adverse events, timescale factors, topology, financial incentives and people's sense of cause and effect. Two basic aspects of n-3 HUFA that are overlooked in CVD dynamics are saturable, hyperbolic responses of the enzymes continually supplying n-6 HUFA and hard-to-control positive feedback receptor signals by excessive n-6 HUFA-based mediators. Multiple feedback loops in inflammation and thrombosis have diverse mediators, and reducing one mediator that occurs above its rate-limiting levels may not reduce the pathophysiology. Clinicians have developed some successful interventions that decrease CVD deaths in the form of secondary prevention. However, the current high CVD prevalence in the USA remains unchanged, and successful primary prevention of CVD remains uncertain. This review weighs the available evidence to help clinicians, the biomedical community and the public put the use of fish oil supplements into a balanced perspective.

A long-term risk-benefit analysis of low-dose aspirin in primary prevention

BACKGROUND

The long-term risk-benefit effect of occasional and regular use of low-dose aspirin (≤ 100 mg per day) in primary prevention of vascular diseases and cancers was calculated.

METHODS

One representative database of 1 000 000 participants from Taiwan's National Health Insurance scheme in 1997-2000 was used. The potential study subjects were those aged 30-95 years, were found not to have been prescribed aspirin before 1 January 2000, but to have first been prescribed low-dose aspirin (≤ 100 mg per day) after that date and were followed up to 31 December 2009. Participants prescribed low-dose aspirin < 20% during the study period were considered occasional users and those prescribed ≥ 80% regular users. After the propensity score matching, rate differences of haemorrhage, ischaemia and cancer between these users were calculated their net clinical risk.

RESULTS

A total of 1720 pairs were analysed. During the study period, haemorrhage and ischaemia occurred in 25 (1·45%) and 67 participants (3·90%) in occasional users and 69 (4·01%) and 100 participants (5·81%) in regular users, whereas cancer occurred in 32 participants (1·86%) in occasional users and 26 participants (1·51%) in regular users. The crude and adjusted net clinical risks of low-dose aspirin use between the two frequency of users (≥ 80% vs. < 20%) were 4·12% (95% CI = 2·19%, 6·07%; P < 0·001) and 3·93% (95% CI = 2·01%, 5·84%; P < 0·001).

CONCLUSIONS

A long-term regular use of low-dose aspirin might not be better than occasional use in the primary prevention against major vascular diseases and cancer.

A short-term effect of low-dose aspirin on major hemorrhagic risks in primary prevention: a case-crossover design

BACKGROUND

Very few studies have examined the risk of short-term adverse hemorrhage of low-dose aspirin use in primary prevention. This case-crossover study examined the transient effect of low-dose aspirin use on major hemorrhagic risks.

METHODS

A representative database of 1,000,000 patients randomly sampled from the Taiwan's National Health Insurance Research Database in 2000 was analyzed. The study cohort consisted of a total of 501,946 individuals, aged 30-95 years old, at risk of a major bleeding event in 2000. A case-crossover study was used to retrieve data on 10,905 incident patients with major hemorrhagic complications (3,781 cerebral and 7,124 gastrointestinal) and prescribed low-dose aspirin (≤300 mg/day) from 2000-2008. A 56-day time window (∼2 months) was used as the case period for which the odds ratio (OR) was estimated using the ratio of patients exposed during the 56-day case period only (1-56 days before the index date) compared to its corresponding 56-day control period only (57-112 days before the index date).

RESULTS

Four hundred eighty-nine (4.5%) of the 10,905 hemorrhagic patients had used low-dose aspirin during the 56-day case only period; 294 (2.7%) of the same patients had used low-dose aspirin during control only period. Low-dose aspirin use increase the risk of developing a major hemorrhage 1.33-fold (95% CI = 1.13-1.55, P<0.0001). Significance was found prominent in 4,453 non-hypertensive and non-diabetic subjects (Adjusted odds ratio = 1.88, 95% CI = 1.21-2.91).

CONCLUSION

Transient low-dose aspirin use increases risk for major hemorrhagic events in Han Chinese.