Abstract Advances in treatment, common cardiovascular (CV) risk factors and the ageing of the population have led to an increasing number of cancer patients presenting with acute CV diseases. These events may be related to the cancer itself or the cancer treatment. Acute cardiac care specialists must be aware of these acute CV complications and be able to manage them. This may require an individualized and multidisciplinary approach. We summarize the most common acute CV complications of cytotoxic, targeted, and immune-based therapies. This is followed by a proposal for a multidisciplinary approach where acute cardiologists work close together with the treating oncologists, haematologists, and radiation specialists, especially in situations where immediate therapeutic decisions are needed. In this first part, we further focus on the management of acute coronary syndromes and acute pericardial diseases in patients with cancer.