Measurements of left ventricular wall thickness and systolic thickening by M mode echocardiography: Interobserver and intrapatient variability

Abstract We examined interobserver and intrapatient variations in M mode echocardiographic measurements of diastolic and systolic interventricular septal and left ventricular posterior wall thickness and in the calculated percent systolic thickening of both walls. Diastolic measurements were made at the onset of the P wave and at the peak of the R wave of the simultaneously recorded electrocardiograms. In 20 normal subjects and six hypertensive patients, we compared measurements by two independent observers. There was a good correlation between the two observers in measurements of diastolic septal and posterior wall thickness (r > .90), whether or not the thickness was measured before the P wave or at the peak of the R wave. The systolic thickness measurements also correlated well (r > .80). However, the percent of systolic septal and posterior wall thickening as calculated by the two observers varied greatly (r > .60). In 10 normal subjects and the 6 hypertensive patients, two echocardiograms recorded on different days under similar conditions were measured by the same observer. There was a poor correlation in measurements of septal and posterior wall thickness and percent thickening. These data indicate that serial M mode echocardiographic determinations of ventricular wall thickness and percent thickening may show considerable variation because of resolution and definition problems and may be unreliable for quantifying changes in these measures produced by medical or surgical interventions.