A Study to Investigate Safety, Tolerability, Pharmacokinetics, and Pharmacodynamics of AZD4954 in Healthy Adult Participants With or Without Elevated Lipoprotein (a) (Lp[a]) Levels, and Participants With Dyslipidemia

Inclusion Criteria: All Parts: * Participants with plasminogen level (concentration) within normal range at the Screening Visit. * All females must have a negative pregnancy test at the Screening Visit and on admission to the study site. * Females of childbearing potential must not be lactating and if heterosexually active must agree to use an approved method of highly effective contraception. * Females of non-childbearing potential must be confirmed at the Screening Visit. * Sexually active fertile male participants with partners of childbearing potential must adhere to the study specific contraception methods from the time of first administration of study intervention until 3 months after the study Follow-up Visit. Parts A and B (Healthy Participants): * Male and female participants aged 18 to 65 years with suitable veins for cannulation or repeated venipuncture. * Have a body mass index (BMI) between 18 and 35 kg/m² inclusive. * For Japanese and Chinese participants (Parts A and B): 1. A Japanese participant is defined as having both parents and 4 grandparents who are ethnically Japanese. This includes second and third generation Japanese whose parents or grandparents are living in a country other than Japan. 2. A Chinese participant is defined as having both parents and 4 grandparents who are ethnically Chinese. This includes second and third generation Chinese whose parents or grandparents are living in a country other than China. Part B (Healthy Participants): * Participants must have elevated Lp(a) ≥ 30 mg/dL at the Screening Visit. Part B (Participants with Dyslipidemia): * Male and female participants aged 18 to 70 years with suitable veins for cannulation or repeated venipuncture. * Have a BMI \> 18 kg/m². * Participants must have elevated Lp(a) ≥ 70 mg/dL at the Screening Visit. * Participants with a fasting LDL-C ≥ 70 mg/dL and \< 190 mg/L at the Screening Visit. * Participants should be receiving moderate or high-intensity statin therapy for ≥ 2 months prior to the Screening Visit, according to the American College of Cardiology/American Heart Association guidelines on blood cholesterol management. * Participants with documented coronary artery disease, stroke, or peripheral artery disease or at moderate or high risk for an atherosclerotic cardiovascular disease event. * There should be no planned medication or dose change during study participation. Exclusion Criteria: All Parts: * History of any clinically important disease or disorder. * History or presence of gastrointestinal, hepatic, or renal disease or any other condition known to interfere with absorption, distribution, metabolism, or excretion of drugs. * Any clinically important illness, medical/surgical procedure, or trauma within 4 weeks of the first administration of study intervention. * Participants with known bleeding or coagulation disorders. * Participants who have an elevated high-sensitivity C-reactive protein (\> 3 mg/L) or have a prothrombin time/international normalized ratio (PT/INR) or activated partial thromboplastin time (aPTT) \> 1.25 times × upper limit normal (ULN). * Any clinically important abnormalities in hematology, coagulation, clinical chemistry, urinalysis, abnormal vital signs or abnormal laboratory values. * Any positive result on Screening for serum hepatitis B surface antigen (HBsAg), hepatitis B core antibody (HBcAb), hepatitis C virus (HCV) or human immunodeficiency virus (HIV). * Any clinically important abnormalities in rhythm, conduction, or morphology of the resting 12-lead electrocardiogram (ECG) at Screening. * Use of drugs with enzyme inducing properties such as St John's Wort within 3 weeks prior to the first administration of study intervention. Parts A and B (Healthy Participants): * Use of any prescribed or nonprescribed medication including antacids, analgesics (other than paracetamol/acetaminophen), herbal remedies, intake of \> 3 × daily recommended levels of vitamins and minerals during the 2 weeks prior to the first administration of study intervention or longer if the medication has a long half-life. * Current smokers or those who have smoked or used nicotine products. Part B (Participants with Dyslipidemia): * Acute ischemic cardiovascular event in the last 12 months prior to randomization. * Poorly controlled diabetes. * Previous administration of Lp(a) inhibitor. * Have uncontrolled hypertension. * Abnormal vital heart rate.