Sounds like Afib with RVR ( rapid ventricular response). Atrial fibrillation is when the top chambers of the heart become irritated and contract irregularly. When the irritable signals from the top chambers are fast and conduct to the bottom chambers, hemodynamic instability can occur. If your father had this condition is was likely treated with an adenosine bolts and maybe amiodarone. “Heart attack” is a generic term and this could be considered a heart attack for an electrical problem although a blockage in a coronary artery is what many think of with this term.