<P> A defibrillator, an electric device connected to the heart and surgically inserted under the skin, may be recommended . This is particularly if there are any ongoing signs of heart failure, with a low left ventricular ejection fraction and a New York Heart Association grade II or III after 40 days of the infarction . Defibrillators detect potentially fatal arrhythmia and deliver an electrical shock to the person to depolarize a critical mass of the heart muscle . </P> <P> The prognosis after myocardial infarction varies greatly depending on the extent and location of the affected heart muscle, and the development and management of complications . Prognosis is worse with older age, and social isolation . Anterior infarcts, persistent ventricular tachycardia or fibrillation, development of heart blocks, and left ventricular impairment are all associated with poorer prognosis . Without treatment, about a quarter of those affected by MI die within minutes, and about forty percent within the first month . Morbidity and mortality from myocardial infarction has however improved over the years due to earlier and better treatment: in those who have an STEMI in the United States, between 5 and 6 percent die before leaving the hospital and 7 to 18 percent die within a year . </P> <P> Complications may occur immediately following the myocardial infarction or may take time to develop . Disturbances of heart rhythms, including atrial fibrillation, ventricular tachycardia and fibrillation and heart block can arise as a result of ischemia, cardiac scarring, and infarct location . Stroke is also a risk, either as a result of clots transmitted from the heart during PCI, as a result of bleeding following anticoagulation, or as a result of disturbances in the heart's ability to pump effectively as a result of the infarction . Regurgitation of blood through the mitral valve is possible, particularly if the infarction causes dysfunction of the papillary muscle . Cardiogenic shock as a result of the heart being unable to adequately pump blood may develop, dependent on infarct size, and is most likely to occur within the days following an acute myocardial infarction . Cardiogenic shock is the largest cause of in - hospital mortality . Rupture of the ventricular dividing wall or left ventricular wall may occur within the initial weeks . Dressler's syndrome, a reaction following larger infarcts and a cause of pericarditis is also possible . </P> <P> Heart failure may develop as a long - term consequence, with an impaired ability of heard muscle to pump, scarring, and increase in size of the existing muscle . Aneurysm of the left ventricle myocardium develops in about 10% of MI and is itself a risk factor for heart failure, ventricular arrhythmia and the development of clots . </P>

Most common cause of death in acute myocardial infarction