Aspirin is proven to help in preventing the clot inside the coronary artery to develop further. Heparin is a better choice but not easy to handle if there is no medical qualified personnel available to administer. Nitrites (isosorbide dinitrate and derivatives) have only a short-term activity but can relieve extra-strain by reducing heart strain in the first hours after the onset. One should keep in mind that nitrites have a different activity if administered in pills (longer effect) and some types of infarction (right ventricular) represent contra-indications. To be sure one is not wrong, it's worth to administer either per-lingual forms (chewable pills or spray) or ointments/adhesive bands with percutaneous release, which act very shortly and can be interrupted promptly if proven wrong. Nitroglycerine and isosorbide-dinitrate (ISDN) sprays with per-lingual administration are the best in an emergency kit. If wrong, their effect ends within 15-30' since administration or shorter. So a combination of aspirin + ISDN or nitroglycerine spray is indeed the thing to do if a better choice is not available/medical personnel not accessible.

A very important matter : once suspicion of heart attack clear, urgent administration of enzymes which dissolve the clot (streptokinase, urokinase) or other human-derived compounds with fibrinolytic activity within THE FIRST 12 H since the onset of symptoms can result in restitutio ad integrum (complete restoration of threatened heart muscle) whilst temporising too much can lead to the infarction to become irreversible. Such compounds are available in most clinics with modern cardiology facilities. So even if things look so'n so don't waste time ! Better have a false emergency than compromise for good the health of a person. Those treated accurately can benefit of a pretty normal life even after the attack, to an extent that they can even enjoy moderate physical activity.