A clinical trial testing what level of potassium supplements are beneficial after heart surgery

The TIGHT-K STUDY. Arrhythmias on the cardiac intensive care unit - does maintenance of high- normal serum potassium levels matter?

Many people who have heart surgery go on to experience abnormal heart rhythms, particularly atrial fibrillation (AF), which can increase the risk of a blood clot forming inside the heart. It is thought that low levels of potassium in the body put people at risk of developing AF after heart surgery and, to prevent this, people undergoing heart surgery are usually given potassium supplements to keep the levels in their blood at a high normal level. However, there is no evidence that doing this is definitively useful. At the same time, potassium supplements can cause unpleasant side effects such as diarrhoea, sickness and stomach pain. The TIGHT-K clinical trial will test whether keeping blood potassium levels at a high normal level after heart surgery is necessary to prevent abnormal heart rhythms. Around 1700 people who are having coronary artery bypass surgery will be invited to take part in the trial from different UK hospitals. Half of the participants will receive potassium supplements to keep their blood potassium levels at the higher end of normal. The other participants will be treated only if their potassium levels drop below normal. Every patient will wear an electrocardiogram (ECG) monitor for 5 days after surgery to record any abnormal heart rhythms. This trial will provide doctors with important information about how best to supplement potassium levels, ensuring that people having cardiac surgery receive the best possible care after surgery.