ASSESSMENT OF LEFT-VENTRICULAR FUNCTION BY MERIDIONAL AND CIRCUMFERENTIAL END-SYSTOLIC STRESS MINOR-AXIS SHORTENING RELATIONS IN DILATED CARDIOMYOPATHY

Echocardiographic meridional wall stress-endocardial shortening relati ons provide estimates of left ventricular (LV) contractility that do n ot uniformly detect myocardial dysfunction despite severe symptoms in dilated cardiomyopathy. To improve detection of myocardial dysfunction in patients with congestive heart failure (CHF) doe to dilated cardio myopathy, echocardiographic meridional and circumferential end-systoli c stress were related to endocardial and midwall shortening in 42 pati ents (95% dead within a mean of 22 months) with dilated cardiomyopathy and 140 normal subjects. A method to estimate LV long-axis dimension from M-mode minor-axis epicardial measurements was developed in a sepa rate series of 115 subjects. Endocardial shortening to meridional wall stress relation identified 31 of 42 CHF patients falling below the 95 % normal confidence interval of the reference population; use of midwa ll shortening decreased this number to 26 (p = NS). The use of circumf erential wall stress identified 39 of 42 patients with subnormal endoc ardial LV shortening and 41 of 42 patients with depressed midwall perf ormance (p <0.01 vs use of meridional stress), The circumferential/mer idional wall stress ratio was 2.6 +/- 0.5 in normal subjects and 1.3 /- 0.2 in CHI: patients (p <0.0001). Thus, use of circumferential end- systolic stress as the measure of afterload improves the detection of myocardial dysfunction by stress/shortening relations in patients with CHF. The ratio between the 2 stresses decreases with more spherical L V shape. Midwall and endocardial shortening measurements are equivalen t in the setting of thin LV walls as occurs in dilated cardiomyopathy.