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Left ventricular shape, afterload and survival in idiopathic dilated cardiomyopathy
P S Douglas1, R Morrow, A Ioli
1Cardiovascular Section, Hospital of the University of Pennsylvania, Philadelphia 19104.
Insights
Idiopathic dilated cardiomyopathy patients with a more spherical left ventricle shape and uneven stress distribution face poorer survival. Specific echocardiographic measurements can predict mortality risk in these patients.
Area of Science:
- Cardiology
- Biomedical Engineering
- Medical Imaging
Background:
- Idiopathic dilated cardiomyopathy (IDC) is linked to elevated left ventricular wall stress and increased ventricular sphericity.
- Understanding the interplay between cardiac shape, afterload, and patient survival is crucial for IDC management.
Purpose of the Study:
- To investigate the relationship between left ventricular shape, afterload, and survival in patients with idiopathic dilated cardiomyopathy.
- To identify echocardiographic parameters that predict mortality in IDC patients.
Main Methods:
- Prospective study of 36 patients with cardiomyopathy using two-dimensional echocardiography.
- Measurements included left ventricular dimensions, shape ratios, and calculated meridional and circumferential end-systolic stress.
- Patients were followed for survival, with mortality data analyzed.
Main Results:
- Survivors had smaller end-diastolic short-axis dimensions compared to nonsurvivors.
- A more spherical left ventricle (higher short- to long-axis ratio) was associated with poorer survival.
- Nonsurvivors exhibited more even distribution of stress between meridional and circumferential planes.
Conclusions:
- Improved survival in IDC is associated with specific echocardiographic criteria: end-diastolic short-axis dimension < 7.63 cm, short- to long-axis ratio < 0.76, and meridional/circumferential stress ratio < 0.54.
- Patients meeting all three criteria had a significantly lower mortality rate (28%) compared to those meeting none (100%).
- These findings highlight the prognostic value of cardiac geometry and stress distribution in IDC.
Abstract:
Because idiopathic dilated cardiomyopathy is characterized by elevated wall stress and a more spherical left ventricle, the relations among shape, afterload and survival were examined. Thirty-six patients with cardiomyopathy were prospectively studied by two-dimensional echocardiography. Data included echocardiographic short- and long-axis cavity dimensions, their ratio and, with cuff systolic blood pressure, meridional and circumferential end-systolic stress and their ratios. Survivors (n = 16) were followed up for 52 months (range 40 to 76); nonsurvivors (n = 20) died an average of 11 months after study. Survivors had a smaller left ventricular end-diastolic short-axis dimension (6.4 versus 7.1 cm, p less than 0.03) but a similar long-axis length (8.6 versus 8.3 cm). However, overall cavity shape or the ratio of short- to long-axis end-diastolic dimensions was more spherical in those with poorer survival (ratio 0.76 versus 0.68, p less than 0.02). Meridional and circumferential end-systolic stresses were similar in the two groups, but stress was more evenly distributed in the long- and short-axis planes in nonsurvivors (meridional/circumferential stress ratio 0.57 versus 0.52 in survivors, p less than 0.05). Improved survival was associated with an end-diastolic short-axis dimension less than 7.63 cm, a short- to long-axis ratio less than 0.76 and a meridional to circumferential stress ratio less than 0.54. Life table analysis revealed a 28% mortality rate in patients with all three of these characteristics compared with 100% in patients with none. Survivors and nonsurvivors did not differ in systolic cavity dimension, wall thickness, relative wall thickness, cavity volume, percent posterior wall thickening or fractional shortening.(ABSTRACT TRUNCATED AT 250 WORDS)