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A study of the relationship between the frequency of labelled pyrophosphate detection in the heart muscle and the incidence of clinical signs of heart failure or angina in 185 postmyocardial-infarction patients demonstrated that the distribution of patients with postinfarction cardiosclerosis among the positive and negative 99mTc-pyrophosphate scintigraphy groups was governed by the presence of heart failure in these patients, a finding suggestive of the scarry fields within the myocardium as the principal cause of myocardial accumulation of labelled pyrophosphate in postinfarction cardiosclerosis. Pyrophosphate accumulation in patients with postinfarction cardiosclerosis can be regarded as an indicator of unfavorable developments, as confirmed by one-year follow-up results in 114 patients.

The dependence between the severity of cardiac insufficiency and the size of the necrotic lesion of the heart muscle, measured according to the area of 99m Tc-pyrophosphate cumulation and the rate of liberation of the isoenzyme MV creatine phosphokinase into the blood, was studied in 77 patients with myocardial infarction in the acute period of the disease. It was demonstrated that the severity of left ventricular insufficiency is directly dependent on the size of necrosis of the heart muscle. Not only the size of the necrotic focus but also the state of the contractility of the other parts of the myocardium is an important factor determining the origin and severity of cardiac insufficiency.

In a study of 46 patients with acute posterior myocardial infarction and different patterns of the necrotic period, anatomical measurements of necrosis weight were compared with the measurements of R wave amplitude and the depth of Q and S waves (the QS complex), recorded from standard leads and precordial mapping, and with serum CPK-MB activity. The results of this comparison suggest that the rate of necrosis formation can be assessed on the basis of variation in the ventricular complex, recorded from standard ECG leads. Electrocardiographic criteria of the severity of the necrotic stage of posterior myocardial infarction and repeated necrosis formation are identified.

A study of 61 patients with acute left ventricular posterior myocardial infarction examined ventricular complex variations, recorded from standard and precordial leads; in fatal cases, ECG findings were compared with pathoanatomical studies of the heart. Precordial mapping was shown to considerably increase the efficiency of electrocardiographic diagnosis of posterior myocardial infarction, permitting more accurate assessment of the site and spread of the infarction focus. Changes of the ST segment and summary R(V1-V4)20 amplitude may serve as an indicator of the severity of posterior myocardial infarction, and an instrument of early outcome prognosis.