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An echocardiographic evaluation of patients with idiopathic heart failure
B Andersson1, K Caidahl, F Waagstein
1Wallenberg Laboratory for Cardiovascular Research, Sahlgrenska University Hospital, Göteborg University, Sweden.
Insights
Idiopathic dilated cardiomyopathy (IDCM) diagnosis is challenging. This study identified 30% of patients with idiopathic congestive heart failure (CHF) as having IDCM, providing reference values for diagnosis.
Area of Science:
- Cardiology
- Internal Medicine
- Echocardiography
Background:
- Idiopathic dilated cardiomyopathy (IDCM) lacks a clear definition in medical literature.
- Congestive heart failure (CHF) of unknown cause requires further investigation for accurate diagnosis.
Purpose of the Study:
- To identify cases of IDCM in patients with unexplained CHF.
- To provide detailed echocardiographic data and assess diastolic dysfunction in IDCM patients.
- To establish reference values for diagnosing IDCM.
Main Methods:
- Retrospective analysis of 2,711 hospital records from western Sweden (16-65 years old) over 6 years.
- Diagnostic investigation including echocardiography for 411 patients with unexplained CHF.
- Comparison with a control group (n=103) to define reference levels for left ventricular (LV) dilatation and ejection fraction (EF).
Main Results:
- 30% of investigated patients (293/411) met criteria for IDCM (LV dilatation and systolic dysfunction).
- 44% of patients without systolic dysfunction showed signs of diastolic dysfunction.
- Ejection fraction (EF), left atrial dimension, and first third filling fraction accurately differentiated patients from controls (98% positive predictive accuracy).
Conclusions:
- Idiopathic dilated cardiomyopathy (IDCM) was identified in 30% of patients with idiopathic congestive heart failure (CHF).
- Echocardiographic parameters including EF, left atrial dimension, and filling fraction are crucial for diagnosing IDCM.
- Reference values and a diagnostic tool for systolic and diastolic dysfunction in IDCM are provided.
Abstract:
The primary myocardial disease idiopathic dilated cardiomyopathy (IDCM) is not clearly defined in the literature. The description is both morphologic and etiologic. We examined consecutive patients with congestive heart failure (CHF) of unknown cause to identify possible cases of IDCM and to give a detailed description of echocardiographic data and possible diastolic dysfunction in this group. The hospital records of patients aged 16 to 65 years hospitalized due to CHF or IDCM during a 6-year period (N = 2,711) were evaluated in a defined region of western Sweden. Twenty-two percent (584/2,711) of these records contained no plausible cause of CHF or IDCM, and among patients being alive, obvious cause was lacking in 411 of 1,516 (27%). These 411 patients were offered a diagnostic investigation, including echocardiography, and they were compared with a randomly selected control group (n = 103) from the general population. Of 411 patients, 293 accepted investigation. From the control group, we defined the reference level for left ventricular (LV) dilatation to be > 32 mm/m2, and reduced ejection fraction according to Teichholz formula to be < 50%. Applying these borderlines, we identified LV dilatation and systolic dysfunction to be present in 30%, either dilatation or systolic dysfunction in 36%, and neither in 34%. In patients without any signs of systolic dysfunction 44% (26/59) showed signs of diastolic dysfunction. In a multivariate analysis, LV dimension was not independently correlated to disease, although LV dimension was univariately correlated to ejection fraction (EF) (r = -0.59; p < 0.0001). However, EF (p < 0.0001), left atrial dimension (p < 0.0001), and the first third filling fraction (p < 0.0001) were the constellation of parameters that most accurately separated patients from controls. By using these three parameters, a positive and negative predictive accuracy of 98% and 61%, respectively, was achieved. Thus, in a consecutive group of patients with idiopathic CHF recruited from a nonselected group of hospitalized patients with CHF, all grades of ventricular function were found. In this group, 30% were identified as having IDCM. We give reference values for the diagnosis of idiopathic IDCM and a simple tool to identify patients with systolic and diastolic dysfunction.