Is ED a sign of heart disease?

Is ED a sign of heart disease? The question usually arrives when a sexual-health problem stops looking like a stand-alone problem. At that stage, the useful move is to read what published sources actually say.
What the published research connects
Harvard Health Publishing answers this directly: "Erectile dysfunction, as it is formally known, is often an early warning sign of heart disease or other circulatory problems."
The language is that of warning. It does not say heart disease is present. A warning sign asks for a closer look and does not hand you a diagnosis.
How to read a warning sign
The Physicians Committee for Responsible Medicine article on ED as an early sign of heart trouble is another source on the same question. The Cleveland Clinic overview of causes, diagnosis and treatment and the MedlinePlus page on erectile dysfunction give you the wider picture to read alongside it.
Taking the heart question to a clinician
The next stage is a visit with a clinician who can look at the whole picture, not only the erection problem. Bring the question in those words. Ask whether your heart health should be checked.
Why the cause comes before the treatment
If erectile dysfunction shows up, the plan changes from "which treatment" to "what else is going on." Settle that first. A treatment chosen without that step is a plan built on half the facts.