 Re: ...he is grave risk of a heart attack.
The first is not correct - they've obviously left "at" out by mistake. A typing error, or a cut.and-paste error probably.
However, the second and third are fine.
Here are a couple of examples without the article...
Sensitive information on millions of US military personnel and veterans remains at grave risk because of weak security controls
A top official for the UN's relief agency Sunday said three million people in Afghanistan are at grave risk
And some more with the article...
Asking for the patient in the ambulance to be taken to another unit puts that patient at a grave risk, but the alternative...
...than recent authors who have hinted at a grave risk of sudden death.
“Here, the children were put at a grave risk of death,” Bell told the judge |