Yes it's still possible to have another heart attack after having a stent put in.
Having a heart stent put in helps with the current heart attack you're having or have had but the stent does not prevent future heart attacks.
The stent does help lessen the chance of a future heart attack but it doesn't prevent future heart attacks.
Even when you have a stent put into your heart you still have the heart disease and need to take care and be prepared in case of another heart attack.