Ventricular function following myocardial infarction : the prognostic value of radionuclide ventriculography
Dewhurst, Neil Gordon
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Ventricular performance was assessed in one hundred consecutive patients recovering from their first myocardial infarction using the non-invasive technique of radionuclide ventriculography. This method was successfully performed in almost 100% of cases and repeated studies had a high degree of patient acceptability; the results were reproducible and easy to interpret and quantify with relative observer independence. Gated blood pool imaging performed prior to discharge from hospital revealed significant impairment of left ventricular function in the majority of patients, often when not clinically suspected. Those patients recovering from anterior infarction had greater reduction in left ventricular ejection fraction with a higher incidence of the more severe abnormalities of regional ventricular wall motion. A system of paradox imaging proved an accurate method for the detection of ventricular dyskinesis, present in 25% of all patients recovering from infarction. Subclinical right ventricular dysfunction occurred in over 40% of those recovering from inferior infarction and the variable degree of right ventricular necrosis contributed to enzymatic indices of infarct size accounting for the relative sparing of left ventricular function. Left ventricular failure and serious arrhythmia in the acute phase were both associated with marked reduction of ejection fraction in the convalescent phase. Low resting ejection fraction at discharge failed to improve in the subsequent year and was associated with the development of left ventricular failure, ventricular arrhythmia and sudden death. Reduction in ejection fraction during exercise testing performed four weeks after discharge had greater sensitivity and specificity than conventional electrocardiographic criteria in the prediction of the development of post-infarction angina which also carried a considerable risk of sudden death. The results of radionuclide ventriculography at rest and during exercise identified as "high risk" 11 of the 13 patients who were to die in the following year and proved more accurate than the Coronary Care Indices currently in use. The implications of these results are related to conventional clinical practice and the development of these and other radionuclide techniques to measure different parameters of ventricular function are discussed.