Left Ventricular Size and Function and Heart Size in the Year Following Myocardial Infarction

Abstract

SUMMARYInterrelationships among left ventricular (LV) size, LV function, and heart size were investigated in 49 patients studied 2-12 months after myocardial infarction. LV end-diastolic volume (EDV) and ejection fraction (EF) were determined by biplane ventriculography. Heart size was estimated from chest films by the cardiothoracic ratio (CTR) and cardiac volume (CV) methods. Ventricular function (i.e., EF) was related to chamber size (i.e., EDV), but the correlation coefficient was not high (r = 0.74); thus, chamber size was not an accurate predictor of EF. Because of the close linear relation that exists between LV end-systolic volume and EDV (r = 0.98), a hyperbola describes the relation between EF and EDV. In general, EF was depressed (<0.50) when EDV exceeded 70 ml/m2, was <0.35 when EDV exceeded upper normal limits (110 mI/M2), and was <0.25 with chamber size >150 mI/M2. Thus relatively small chamber size (<150 ml/m2) was associated with a wide range in ventricular function, while large chamber size was associated with severe dysfunction (EF < 0.30). By either heart size method, cardiomegaly (CTR > 0.50 or CV > 540 ml/m') was not found consistently until EDV exceeded 150 ml/m'. Hence normal heart size was often associated with moderate EF depression (0.49-0.30), while cardiomegaly was often associated with severe dysfunction. Clinical heart failure (CHF) was usually accompanied by EF < 0.30, but chamber size ranged from 101 to 331 ml/m2. Primarily because of this variation in chamber size, both normal heart size and cardiomegaly were at times associated with CHF.The poor correlations of EF with CTR (r = -0.43) and CV (r = -0.52) preclude use of the heart size indices as accurate predictors of LV function. When the data were analyzed according to the presence or absence of cardiomegaly, the following generalizations could be made regardless of the heart size method used. Cardiomegaly was a reasonable indicator of postinfarction LV function, being associated with depressed function and often with CHF. However normal heart size was associated with either normal LV function, or commonly, with depressed function, often not clinically apparent. Additional Indexing Words:Clinical heart failure Ejection fraction Ventricular volume IT IS WIDELY RECOGNIZED that myocardial infarction involves predominantly the left ventricular (LV) wall and that infarction may produce impairment in LV function and an increase in chamber size. In postinfarction patients the clinician attempts to determine LV size in order to assess the magnitude

Utility of Phase Standard Deviation and Histogram Bandwidth, Derived from Phase Analysis, as Clinical Indicators of Heart Failure

“…LVEDV/LVESV negatively correlated with LVEF. In general, the bigger cardiac size is, the worse cardiac function becomes (23). Therefore, increases in PhHB/PhSD indicate LV structural and functional changes.…”

Imaging of ischemic heart disease

“…Left ventricular dilatation usually signifies prior myocardial infarction, or association of another form of acquired cardiovascular disease, such as chronic systemic hypertension. Left ventricular function in these patients is usually impaired [14]. The radiographic appearance of the heart in patients having their first acute myocardial infarction has important prognostic value.…”

“…The radiographic appearance of the heart in patients having their first acute myocardial infarction has important prognostic value. Normal cardiac size after acute myocardial infarction is associated with better cardiac function [14] and outcome [15].…”

Usefulness and limitations of thallium-201 myocardial scintigraphy in delineating location and size of prior myocardial infarction.

“…Previous studies have shown that an ACS < 8% has no demonstrable effect on LV function. [1][2][3] Thus, the inability of 20'Tl scintigraphy to detect scars of this size is not a great disadvantage. A negative 20'Tl myocardial scintigram does not exclude the possibility of a prior infarction, but makes the presence of a significant scar highly unlikely.…”