The treatment of patients with chronic heart failure and those with asymptomatic left ventricular (LV) dysfunction has focused primarily on patients with LV enlargement and a low ejection fraction (EF). Little attention has been paid to those with a normal chamber size and a low EF. We sought to examine the LV geometry and clinical characteristics in such patients with nondilated cardiomyopathy. Of 3,350 transthoracic echocardiograms performed during a 6-month period, 696 showed an EF of ≤0.45. The patients with an end-diastolic diameter of >56 mm, regional wall motion abnormalities, or valvular disease were excluded. Of the 696 patients, 98 met these criteria, and their medical records were reviewed. The average age was 71 ± 14 years, and 56% were men. Common co-morbidities included hypertension in 52% and atrial fibrillation (AF) in 43%. Only 22% had disabling cardiac symptoms (functional class III or greater). The average end-diastolic dimension was 49 ± 5 mm, and the EF was 34 ± 8%. LV hypertrophic remodeling was present in 53%. A second echocardiogram (422 ± 177 days after the baseline study) was available for 54 patients. The chamber size was unchanged, but the EF had increased from 33 ± 8% to 40 ± 14% (p <0.01). The improvement in EF was seen in the group with AF (33 ± 6% to 44 ± 15%, p <0.01) but not in those with normal sinus rhythm (33 ± 9% to 37 ± 12%, p = NS). In conclusion, 14% of patients with an EF of ≤0.45 had nondilated cardiomyopathy, often with LV hypertrophic remodeling and/or AF. An improvement in LV function can be expected in many patients with nondilated cardiomyopathy, particularly those with AF.
Structural and functional remodeling of the left ventricle follows a variety of cardiac overloads and/or injuries. For example, ventricles subjected to pressure overload with systemic arterial hypertension often exhibit hypertrophic or concentric remodeling with a normal chamber size and a normal ejection fraction (EF) but abnormal diastolic function. In others with dilated cardiomyopathy, substantial left ventricular (LV) dilation and remodeling, with eccentric hypertrophy, afterload excess, and a depressed EF, are often present. Others will exhibit a low EF with little or no LV enlargement. Such patients with nondilated cardiomyopathy will have clinical features that resemble those seen in dilated cardiomyopathy; however, considerable variation appears to exist in the clinical outcomes, with some patients requiring cardiac transplantation and others having a relatively benign clinical course. We sought to further define the clinical features of patients with this less common pattern of LV remodeling. We performed a retrospective analysis of the clinical records of 98 patients with LV systolic dysfunction occurring in the absence of chamber enlargement. We report on the prevalence and clinical characteristics of this less familiar pattern of LV remodeling.
Methods
All transthoracic echocardiogram reports from December 2005 through May 2006 were screened, and those showing an EF of ≤0.45 and a normal LV end-diastolic dimension were selected for analysis. A normal value for the end-diastolic diameter was defined as ≤56 mm. The patients with congenital, valvular, or overt coronary heart disease (ie, LV asynergy) were excluded, as were 2 patients with known cardiac amyloid.
Two-dimensional and M-mode echocardiograms were performed using commercially available equipment and standard techniques that we have used in the past. The EF was determined using the Teicholz method, supplemented by visual inspection. For the purposes of analysis, we examined those with clear and obvious LV systolic dysfunction (EF ≤0.30) and compared them to those who had mild to moderate LV dysfunction (EF >0.30). The LV mass was calculated using the method of St. John Sutton et al. The relative wall thickness was determined as the ratio of end-diastolic wall thickness to the end-diastolic radius, where the radius was 1/2 the echocardiographic minor axis diameter. Our definitions of concentric remodeling and concentric hypertrophy have been previously published.
Our study involved a retrospective review of records that were generated during standard medical care. The institutional review board of the Lahey Clinic approved the study.
Results
Of the 3,350 transthoracic echocardiograms performed during the 6-month review period, 696 exhibited an EF of ≤0.45. Of these 696 patients, 98 had a normal LV chamber size, no LV asynergy, and no significant valvular heart disease. These 98 patients met our criteria for the diagnosis of nondilated cardiomyopathy. Thus, the prevalence of nondilated cardiomyopathy in this population of patients with LV systolic dysfunction was 14%.
The clinical characteristics of the 98 patients are listed in Table 1 . A history of hypertension was present in approximately 1/2 of our patients. Atrial fibrillation (AF) was present in 43%. Other conditions were less frequently seen. Those with an EF of ≤0.30 were significantly more symptomatic than those with an EF >0.30. With this sole exception, the clinical characteristics were similar in those with an EF >0.30 and <0.30. Of the 22 symptomatic patients, brain natriuretic peptide data were available for 15; in this subgroup, the brain natriuretic peptide level ranged from 176 to 2,600 pg/ml (average 716 ± 612).
| Variable | All Patients (n = 98) | Ejection Fraction | |
|---|---|---|---|
| ≤30% (n = 41) | >30% (n = 57) | ||
| Age (years) | 71 ± 14 | 72 ± 15 | 71 ± 13 |
| Men | 55 (56%) | 20 (49%) | 35 (61%) |
| Body surface area (m 2 ) | 1.9 ± 0.2 | 1.8 ± 0.2 | 1.9 ± 0.2 |
| Body mass index (kg/m 2 ) | 27 ± 5 | 26 ± 6 | 27 ± 5 |
| Hypertension | 51 (52%) | 20 (49%) | 31 (54%) |
| Atrial fibrillation | 42 (43%) | 17 (42%) | 25 (44%) |
| Bundle branch block | 35 (36%) | 17 (42%) | 18 (32%) |
| Diabetes mellitus | 27 (28%) | 14 (34%) | 13 (23%) |
| NYHA class III-IV | 22 (22%) | 15 (37%) | 7 (12%) ⁎ |
| Chronic kidney disease | 19 (19%) | 10 (24%) | 9 (16%) |
| Hypothyroidism | 14 (14%) | 4 (10%) | 10 (18%) |
The echocardiographic data are listed in Table 2 . The average LV end-diastolic diameter was normal (2.6 ± 0.4 mm/m 2 body surface area). It was slightly larger in the subgroup with an EF of ≤0.30 than in the subgroup with an EF >0.30. Concentric remodeling (defined as a relative wall thickness >0.43) was present in 41%, and LV hypertrophy (mass >105 g/m 2 ) was present in 12%. Thus, LV hypertrophy or concentric remodeling was present in >1/2 of the patients. Concentric remodeling was seen in 53% of the patients with an EF >0.30 and in 29% of those with an EF of ≤0.30 (p <0.05); however, the difference in the prevalence of LV hypertrophy in these 2 groups (8% and 19%, respectively) was not statistically significant.
| Variable | All Patients | Ejection Fraction | |
|---|---|---|---|
| ≤30% | >30% | ||
| Ejection fraction (%) | 34 ± 8 | 25 ± 5 | 39 ± 4 |
| Left ventricular end-diastolic dimension (mm) | 49 ± 5 | 51 ± 4 | 48 ± 5 ⁎ |
| Relative wall thickness | 0.43 ± 0.10 | 0.41 ± 0.11 | 0.44 ± 0.09 |
| Left ventricular mass (g/m 2 body surface area) | 88 ± 21 | 94 ± 23 | 83 ± 18 † |
| Left atrial dimension (mm) | |||
| Sinus rhythm | 39 ± 7 | 38 ± 6 | 40 ± 7 |
| Atrial fibrillation | 45 ± 7 | 44 ± 6 | 47 ± 7 |
A second or repeat echocardiogram was available for 54 patients (average 422 ± 177 days after the baseline study). These data are listed in Table 3 . When the baseline and follow-up data were examined, no significant change was found in the LV end-diastolic dimension; however, the EF did increase (p <0.01) during this period. The increase in EF was statistically significant in the patients whose baseline characteristics included AF but not in those who were in normal sinus rhythm. In the patients with a history of hypertension, a tendency was seen for the EF to increase (33 ± 8% to 39% ± 15%) but this change (driven largely by the presence of AF in 1/2 of this subgroup) did not reach statistical significance. Likewise, no significant EF change was seen in the subgroups with diabetes mellitus, renal insufficiency, or hypothyroidism.
| Variable | Baseline | Follow-Up (Average 422 days) |
|---|---|---|
| Diameter (mm) | ||
| All patients | 50 ± 5 | 50 ± 6 |
| Sinus rhythm | 50 ± 6 | 51 ± 6 |
| Atrial fibrillation | 49 ± 4 | 48 ± 5 |
| Ejection fraction (%) | ||
| All patients | 33 ± 8 | 40 ± 14 ⁎ |
| Sinus rhythm | 33 ± 9 | 37 ± 12 |
| Atrial fibrillation | 33 ± 6 | 44 ± 15 ⁎ |
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