I. Cardiac dysfunction – Involvement of a large portion of heart muscles can affect the pumping function of the heart. This may be reflected as sudden breathlessness (Acute left ventricular failure) or a fall in blood pressure (cardiogenic shock). These complications can be managed by drugs but in severe cases, mechanical assistance by an intraaortic balloon pumping system (Aortic counterpulsation) may be needed.

II. Disturbance in the normal rhythm of the heart (Arrhythmia) – Disturbance in rhythmic contraction of the heart is one of the most common complications. Fortunately, most of them are not very serious. Deficient blood supply in the heart muscles, electrolyte disturbance and autonomic imbalance are factors that contribute to disturbance in the normal rhythm of the heart. Rest, pain relief, correction of electrolyte imbalance and reassurance can prevent arrhythmias. However, complications like ventricular tachycardia and fibrillation are serious and require immediate measures (drug therapy or DC shock).

III. Recurrent angina – Recurrent or persistent chest discomfort is a common complication of heart attack especially, after the successful dissolution of a clot (thrombolysis). It often denotes extension of the damage and repeat thrombolysis or angioplasty may be required.

IV. Pericarditis – Involvement of the outer covering (pericardium) of the heart may also cause chest pain. But unlike anginal pain, it increases while inhaling and decreases on sitting and leaning forward. This pain responds to aspirin. Dressler’s syndrome is form of pleuro-pericardial chest pain associated with fever occurring few days to 6 weeks after heart attack. This also responds to treatment with aspirin.

V. Clot embolism – Blood clot (thrombus) formed inside the heart or in veins of the leg may detach itself and block the circulation at distant site. If it reaches the lungs or brain, it could lead to pulmonary infarction and stroke. Anticoagulant therapy (e.g. heparin) helps decrease the incidence of such episodes.

VI. Mechanical complications – Necrosis (death) of the muscles may cause mechanical defects which could disturb the functioning of the heart (Cardiac failure) or cause fall in blood pressure (Cardiogenic shock). There may be perforation (hole) in the septum (partition) dividing the two chambers of the heart (ventricular septal defect),  rupture of the muscle which stabilises the valve leaflets (Papillary muscle rupture) or even rupture of the muscle wall.

VII. Aneurysm of left ventricle – This is a late complication of heart attack in which the necrosed area move paradoxically increasing the work load on remaining viable heart muscles. The chances of clot formation and detachment (embolism) leading to serious consequences as well as abnormal rhythm of heart (arrhythmia) is increased in cases of aneurysmal dilation.