Left atrial systolic function is depressed in idiopathic and preserved in ischemic dilated cardiomyopathy

Background Left atrial systolic dysfunction, unexplained by altered loading conditions, has been reported in idiopathic dilated cardiomyopathy suggest ing left atrial involvement in the myopathic process. Materials and methods Seventeen patients with idiopathic dilated cardiomyop athy, 16 with ischemic dilated cardiomyopathy and 18 normal controls were s tudied with transthoracic echocardiography and cardiac catheterization. Tra nsmitral diastolic flow was evaluated with pulsed Doppler. Left atrial volu me (cm(3)/m(2)) at mitral valve opening (maximal, V-max), onset of atrial s ystole (P wave of the electrocardiogram, Vp), and mitral valve closure (min imal, V-min) was determined with two-dimensional echocardiography using the biplane area-length method. The left atrial active emptying fraction (ACTE F = [Vp-V-min.] x 100/Vp) served as an index of systolic function. Results The peak early diastolic transmitral flow velocity (cm/sec) was sim ilar in the three groups (idiopathic: 60 +/- 16, ischemic: 58 +/- 20, contr ol: 56 +/- 22; P = NS), whereas the late diastolic transmitral flow velocit y was lower but not significantly different in idiopathic compared to ische mic cardiomyopathy, and in both was lower than control (26 +/- 12 vs. 34 +/ - 13 vs. 44 +/- 14, respectively; P < 0.05). V-max. and Vp were similar in idiopathic and ischemic cardiomyopathy and greater than control (44.6 +/- 1 3.6 vs. 48.2 +/- 18.3 vs. 26.9 +/- 6.2; P < 0.05, and 34.6 +/- 13.4 vs. 30. 8 +/- 10.9 vs. 16.7 +/- 3.7, respectively; P < 0.05). ACTEF was lower in id iopathic than in ischemic cardiomyopathy and in the latter it was similar t o control (18 +/- 10% vs. 32 +/- 10% vs. 36 +/- 10%, respectively; P < 0.05 ). Moreover, ACTEF was inversely related to left atrial tension at end-of a trial systole both in idiopathic and in ischemic cardiomyopathy (r(2) = 0.5 2, P = 0.001 and r(2) = 0.57, P = 00007, respectively). However, at any giv en level of left atrial tension at end of atrial systole, ACTEF was lower i n idiopathic than ischemic cardiomyopathy. Conclusion Left atrial systolic function is depressed in idiopathic and pre served in ischemic dilated cardiomyopathy despite similar left atrial loadi ng conditions. This finding suggests left atrial myopathy in the former, an d may be related to the differences in the response to medical treatment an d clinical outcome observed between the two conditions.