To assess outcomes and predictors of long-term myocardial dysfunction after cardiac arrest (CA) of cardiac origin. We retrospectively included consecutive, single-center, prospective-registry patients who survived to hospital discharge for adult out-of-hospital and in-hospital CA of cardiac origin in 2005-2019. The primary objective was to collect the 1-year New York Heart Association Functional Class (NYHA-FC) and major adverse cardiovascular events (MACE). Of 135 patients, 94 (72%) had their NYHA-FC determined after 1 year, including 75 (75/94, 80%) who were I, 17 (17/94, 18%) II, 2 (2/94, 2%) III, and none IV. The echocardiographic left ventricular ejection fraction was abnormal in 87/130 (67%) patients on day 1, 52/123 (42%) at hospital discharge, and 17/52 (33%) at 6 months. During the median follow-up of 796 [283-1975] days, 38/119 (32%) patients experienced a MACE. These events were predominantly related to acute heart failure (13/38) or ischemic cardiovascular events (16/38), with acute coronary syndrome being the most prevalent among them (8/16). Pre-CA cardiovascular disease was a risk factor for 1-year NYHA-FC > I (P = 0.01), absence of bystander cardiopulmonary resuscitation was significantly associated with NYHA-FC > I at 1 year. Most patients had no heart-failure symptoms a year after adult out-of hospital or in-hospital CA of cardiac origin, and absence of bystander cardiopulmonary resuscitation was the only treatment component significantly associated with NYHA-FC > I at 1 year. Nearly a third experienced MACE and the most common types of MACE were ischemic cardiovascular events and acute heart failure. Early left ventricular dysfunction recovered within 6 months in half the patients with available values.