Q What is my ‘QT interval’ and why is it getting longer?

AQT interval is the measurement, identified on an electrocardiogram (ECG), between the heart contracting and relaxing. If this interval is ‘prolonged’, you may be at increased risk of abnormal heart rhythms or even cardiac arrest, and it can be present from birth (genetic long QT syndrome), or develop later in life. There may be no symptoms, but found coincidentally during ECGs for other reasons. It may cause palpitations or blackouts, with a small risk of irregular heartbeat, which, if not treated urgently, can be fatal. The QT interval can slowly get longer as you age, but may also be prolonged by medications such as certain antibiotics, antihistamines, heart medicines, diuretics and antidepressants. You should be referred for further testing by a cardiologist, plus lifestyle advice about avoiding stress, strenuous exercise or dehydration/salt depletion. Treatments may include potassium supplements, beta blockers to control the beat, or even fitting of a pacemaker or internal defibrillator.