Clwyd West AM Darren Millar 999 heart attack priority worry
Wales is the only UK nation to see an improvement in the time it takes ambulances to reach the most critical 999 calls, BBC research has found.
While response times to life-threatening incidents have lengthened elsewhere, new figures suggest Welsh ambulances arrive more quickly.
But Clwyd West AM Darren Millar has raised the case of a man who collapsed while walking in Llandudno with a suspected heart attack but had to wait 35 minutes for an ambulance.
He said he found that the man - who survived - did not qualify for an ambulance within eight minutes because he was not unconscious or under cardiac arrest.
Mr Millar said patients suffering suspected heart attacks or chest pains should be included in the most critical of cases.
Health Secretary Vaughan Gething said those who most need the fastest response get it.