Although relatively rare, cardiac metastases represent a significant clinical challenge because of their impact on cardiac function and overall patient prognosis. This case presents a rare and atypical presentation of a patient with ventricular arrhythmia revealing a metastatic cancer in the heart. A 59-year-old man with lung cancer was admitted for chest tightness and episodes of syncope. Cardiac high-sensitivity troponin was negative. An electrocardiogram showed runs of sustained ventricular tachycardia, whereas an echocardiogram revealed hypokinesis in the anterolateral/anterior left ventricular (LV) walls. Coronary angiogram was normal. Cardiovascular magnetic resonance imaging (CMR) showed a large inhomogeneous lesion of the LV midanterior wall with a peripheral component of hyperenhancement and a central core with clear hyposignal, adjacent to the pulmonary carcinomatous mass. Because the patient had a poor short-term prognosis, medical treatment and palliative care were proposed. In the management of patients with myocardial metastasis, CMR is important in the diagnostic workup of cardiac masses, prognosis and treatment, negative troponin, and ventricular arrhythmia.