silent ischemia

Silent ischemia is the heart running short of blood without ringing any alarm bell. The muscle is under-supplied, just as it would be in angina, but the person feels no chest pain at all — the warning system simply does not fire.

The under-perfusion is real and can be documented: the ECG may show ST changes during a stress test, or monitoring may capture transient ischemia during ordinary activity, all without symptoms. Why pain is absent is not fully understood; reduced sensitivity of pain pathways is thought to play a part, which is why it is especially common in people with diabetes, who can have impaired nerve signalling.

Its danger lies precisely in the missing warning. Without the prompt of pain, episodes go unnoticed and the person does not slow down or seek help, so the same total burden of ischemia carries the same risks while being harder to detect. It is often found incidentally on testing or monitoring rather than because of complaints.

Silent ischemia is the same underlying process as symptomatic ischemia, distinguished only by the absence of perceived symptoms; some patients have a mix of silent and painful episodes.