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Left atrial systolic function is depressed in idiopathic and preserved in ischemic dilated cardiomyopathy
F Triposkiadis1, I Moyssakis, L Hadjinikolaou
1University of Thessaly, Faculty of Health Sciences, School of Medicine, Larissa, Greece. filtrip@yahoo.com
Insights
Left atrial systolic function is impaired in idiopathic dilated cardiomyopathy but preserved in ischemic dilated cardiomyopathy, suggesting a primary left atrial myopathy in the idiopathic form. This difference may impact treatment response and clinical outcomes.
Area of Science:
- Cardiology
- Cardiac Physiology
- Echocardiography
Background:
- Idiopathic dilated cardiomyopathy (IDC) is associated with left atrial systolic dysfunction.
- This dysfunction occurs independently of altered loading conditions, suggesting intrinsic left atrial involvement.
- Understanding this dysfunction is crucial for differentiating IDC from other cardiomyopathies.
Purpose of the Study:
- To investigate and compare left atrial systolic function in patients with idiopathic dilated cardiomyopathy (IDC) and ischemic dilated cardiomyopathy (ICM).
- To determine if left atrial dysfunction in IDC is a primary myopathic process.
- To correlate left atrial function with atrial loading conditions and tension.
Main Methods:
- Studied 17 patients with IDC, 16 with ICM, and 18 controls using transthoracic echocardiography and cardiac catheterization.
- Assessed transmitral diastolic flow with pulsed Doppler.
- Quantified left atrial volumes and calculated the left atrial active emptying fraction (ACTEF) as an index of systolic function.
Main Results:
- Left atrial active emptying fraction (ACTEF) was significantly lower in IDC (18%) compared to ICM (32%) and controls (36%).
- Left atrial volumes (Vmax and Vp) were elevated in both IDC and ICM compared to controls.
- ACTEF showed an inverse relationship with end-systolic left atrial tension in both IDC and ICM, but was lower in IDC at similar tension levels.
Conclusions:
- Left atrial systolic function is depressed in idiopathic dilated cardiomyopathy but preserved in ischemic dilated cardiomyopathy.
- This suggests a primary left atrial myopathy in IDC.
- The findings may explain observed differences in medical treatment response and clinical outcomes between IDC and ICM.
Background:
Left atrial systolic dysfunction, unexplained by altered loading conditions, has been reported in idiopathic dilated cardiomyopathy suggesting left atrial involvement in the myopathic process.
Materials And Methods:
Seventeen patients with idiopathic dilated cardiomyopathy, 16 with ischemic dilated cardiomyopathy and 18 normal controls were studied with transthoracic echocardiography and cardiac catheterization. Transmitral diastolic flow was evaluated with pulsed Doppler. Left atrial volume (cm3/m2) at mitral valve opening (maximal, Vmax.), onset of atrial systole (P wave of the electrocardiogram, Vp), and mitral valve closure (minimal, Vmin. ) was determined with two-dimensional echocardiography using the biplane area-length method. The left atrial active emptying fraction (ACTEF = [Vp-Vmin.] x 100/Vp) served as an index of systolic function.
Results:
The peak early diastolic transmitral flow velocity (cm/sec) was similar in the three groups (idiopathic: 60 +/- 16, ischemic: 58 +/- 20, control: 56 +/- 22; P = NS), whereas the late diastolic transmitral flow velocity was lower but not significantly different in idiopathic compared to ischemic cardiomyopathy, and in both was lower than control (26 +/- 12 vs. 34 +/- 13 vs. 44 +/- 14, respectively; P < 0.05). Vmax. and Vp were similar in idiopathic and ischemic cardiomyopathy and greater than control (44.6 +/- 13.6 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 idiopathic than in ischemic cardiomyopathy and in the latter it was similar to 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 atrial systole both in idiopathic and in ischemic cardiomyopathy (r2 = 0.52, P = 0.001 and r2 = 0.57, P = 0.0007, respectively). However, at any given level of left atrial tension at end of atrial systole, ACTEF was lower in idiopathic than ischemic cardiomyopathy.
Conclusion:
Left atrial systolic function is depressed in idiopathic and preserved in ischemic dilated cardiomyopathy despite similar left atrial loading conditions. This finding suggests left atrial myopathy in the former, and may be related to the differences in the response to medical treatment and clinical outcome observed between the two conditions.