Breathlessness can occur suddenly at rest or can be brought on by exertion. Sometimes patients just notice a gradual reduction in their exercise tolerance; maybe having to stop for breath walking up hill or feeling a bit puffed doing the housework. There are many ways the heart can be the cause of these symptoms of breathlessness. The heart muscle, called the myocardium, may not be working as it should. This is often called ‘heart failure’ a rather frightening phrase that just means that the heart is not pumping enough to keep up with the body’s needs. This leads to breathlessness and sometimes also to fluid retention which may appear as swelling around the ankles and calves. Another common cause of shortness of breath is leaking or narrowing of one of the heart valves. Perhaps the heart has gone ‘out of rhythm’ into atrial fibrillation (AF) which is the commonest of the arrhythmias. For some individuals, especially those with diabetes, coronary disease doesn’t lead to classical chest pain – their angina manifests as breathlessness instead. Cardiologists can diagnose many of these problems from a history and examination. For most patients with shortness of breath the next test is an echocardiogram which will confirm or exclude most heart muscle and valve conditions.