The tool, developed by UK researchers, uses artificial intelligence to detect the earliest signs of a serious condition called “complete heart block”—which can be fatal if left untreated.

Heart block is caused by problems with the electrical signals moving from the upper to lower chambers of the heart as it beats. The signal can only get through sometimes or not at all. (This makes the heart beat more slowly or skip beats.) People with heart block may experience fainting, fatigue, injuries from falls, or even sudden death.

At present, doctors use clues from an ECG—which records the electrical activity of the heart and is one of the most common medical tests in the world—along with international guidelines to identify people who have or are likely to develop complete heart block. But these findings are non-specific and can miss patients who might benefit from earlier treatment—particularly as the abnormal heartbeat in the early stages of the condition can be intermittent.