Background The presence of a left bundle-branch block (LBBB) among firefighters raises questions about stratifying risk of subsequent cardiovascular events as this conduction disorder may mask underlying coronary artery disease. This report describes the case of a firefighter with a history LBBB with exertional dyspnoea of recent onset after work activity.

Case report A 39-year-old male firefighter with LBBB developed exertional dyspnoea after a prolonged session of work. ECG and treadmill test only showed a permanent LBBB; echocardiography and myocardial scintigraphy did not add to this. However, multislice CT (MSCT) showed a significant stenosis in the mid-left anterior descending artery (LAD). Coronary angiography confirmed the stenosis with subsequent placement of a coronary stent.

Conclusions An occupational physician should take into account that factors such as age and low cardiovascular risk do not always exclude heart disease, especially when there are conduction system abnormalities that can mask possible coronary artery disease.