What is often the first indication of metastatic cardiac disease?

The correct response highlights that pericardial effusion is often the first indication of metastatic cardiac disease. When cancer spreads to the heart, it commonly affects the pericardium, the fluid-filled sac surrounding the heart. This can lead to the accumulation of fluid, which is referred to as pericardial effusion. In patients with malignancies, this effusion can develop without significant symptoms initially and may be detected through imaging studies like echocardiography.

In contrast, while arrhythmias can occur in patients with metastatic disease, they are typically not the first clinical sign. Arrhythmias may arise from a variety of causes, including the direct effects of tumors on the myocardium or electrolyte imbalances, but they tend to present later. Myocardial infarction, usually a consequence of coronary artery disease, is unrelated to metastatic disease. Similarly, while valvular dysfunction can occur due to direct tumor involvement or secondary effects, it is also not as common a first presentation as pericardial effusion.