Methods are provided for diagnosis, prognosis, and treatment associated with a cardiovascular event in a subject as well as methods of providing anti-platelet therapy. The methods can comprise obtaining a sample from the subject, and determining the presence of at least two single nucleotide polymorphisms (SNP) in the sample selected from Rs7541936 in PTGER3, Rs977214 in PTGER3, and Rs2206343 in PTGER3. The methods can also comprise determining the presence in the sample of Rs4383756 in PTGER4. Some methods comprise administering conventional anti-platelet therapy to the subject if Rs4383756 in PTGER4 is present in the sample. Furthermore, some methods comprise administering an EP3 antagonist and/or conventional anti-platelet therapy to the subject if Rs4383756 in PTGER4 is not present in the sample. The cardiovascular event can involve thrombosis or an embolic event, a myocardial infarction, a stroke, a primary cardiovascular event, or coronary artery disease.
