Use of QRS scoring and thallium-201 scintigraphy to assess left ventricular function after myocardial infarction

Abstract

To determine the usefulness of the QRS scoring system in predicting left ventricular function, and the correlation between the QRS score, left ventricular ejection fraction, and the size of infarction, patients with acute or chronic infarction were studied by means of 12-lead electrocardiography, rest thallium-201 scintigraphy, and radionuclide angiography. In patients with acute infarction there was a statistically significant correlation between the QRS score and the left ventricular ejection fraction (n = 28, r = −0.61, p < 0.001), between the thallium score (as a measure of the extent of necrosis) and the left ventricular ejection fraction (n = 21, r = 0.70, p < 0.001), and between the QRS score and the thallium score (n = 22, r = −0.65, p < 0.001). A QRS score of 2 or less separated patients with left ventricular ejection fraction of 40% or greater from those with lower left ventricular ejection fraction (p < 0.01). In patients with chronic infarction there was a wide scatter of ejection fraction for any given QRS score (n = 41, r = −0.51). In a subset of patients with chronic infarction before they underwent coronary artery bypass, there was still a fair correlation between thallium score and left ventricular ejection fraction (n = 15, r = 0.61, p < 0.02) but not between thallium score and QRS score (r = 0.03, p > 0.05). In addition, in these patients with chronic infarction who underwent coronary revascularization, there was still a fair correlation between the postoperative thallium score and the postoperative left ventricular ejection fraction (r = 0.75, p < 0.05) but not between the postoperative thallium score and the postoperative QRS score (r = 0.02, p > 0.05) or between the QRS score and the ejection fraction (r = 0.24, p > 0.05). The size of the defect appears related to the left ventricular ejection fraction in both patients with acute infarction and those with chronic infarction. The QRS scoring system in patients with acute infarction and the size of the thallium defect in patients with acute or chronic infarction can categorize patients into those who have a low, moderate, and normal ejection fraction.