A 87-year-old woman was hospitalised because of a third-degree atrioventricular block. After the insertion of a temporary pacemaker lead through the left subclavian vein, she developed an ipsilateral pneumothorax. Although there were clinical and echocardiographic signs of cardiac tamponade after chest tube placement for pneumothorax, a second echocardiogram performed after transportation for surgical drainage failed to demonstrate the presence of any pericardial fluid, while the patient showed an unexpected clinical improvement. A new X-ray showed a collection of left pleural fluid. Over the following days a limited amount of blood was drained through the tube with disappearance of the pleural effusion and no further signs of major bleeding. A permanent DDD pacemaker was subsequently implanted and the patient was discharged in a good condition.