INVESTED will test the hypothesis that high dose trivalent influenza vaccine will reduce cardiopulmonary events to a greater extent than standard dose quadrivalent influenza vaccine in high-risk cardiovascular patients with a recent history of myocardial infarction or heart failure. The trial will enroll 9300 participants over one Vanguard (pilot) season and three additional influenza seasons. The primary endpoint will be a composite of all-cause mortality or cardiopulmonary hospitalization.