Volume 23, Issue 3 , Pages 338-339, March 2010
Response to “Chromosomal Abnormalities and Neuromuscular Disorders Predict Severity and Outcome of Noncompaction in Addition to Cardiac Comorbidities”
Article Outline
- Diagnosis and Follow-Up
- Segmental Analysis
- Measurement
- Associated Pathology
- Acknowledgment
- References
- Copyright
To the Editor:
Drs Stöllberger and Finsterer1 have posed a number of questions about our study on left ventricular noncompaction.2 This response has sections answering questions regarding the diagnosis and follow-up, segmental analysis, echocardiographic measurement, and associated pathology of our study on pediatric left ventricular noncompaction.
Diagnosis and Follow-Up
No interobserver studies were carried out for measurement of the noncompaction/compaction ratio, but in patients with diagnostic challenges, studies were reviewed by both authors to see if they met the criteria for inclusion. All included patients had multiple studies with multiple different readers making the diagnosis of left ventricular noncompaction. Those patients were then carefully examined to confirm if left ventricular noncompaction was present using the 4 criteria listed in our article and described in the literature.2, 3, 4, 5
Autopsy specimens were available for 3 of the patients in our series, and left ventricular noncompaction was verified in all. Figure 1 is an example of left ventricular noncompaction in patient 6 in group 2 (patients who died or needed heart transplantation).
Figure 1
Apical short-axis dissection of a pathologic specimen in a patient who died in our series from left ventricular noncompaction and Ebstein's anomaly. The noncompaction (NC) is noted at the apex of the left ventricle (LV). The tricuspid valve (TV) apparatus is significantly displaced into the apical region, while the right ventricle (RV) demonstrates significant dilation and hypertrophy. The length of the black line represents 1 cm. This image was obtained courtesy of Andrew J. Connolly, MD, PhD, Stanford University, Lucille Packard Children's Hospital. ∗Middle cardiac vein.
As stated in our paper, follow-up was not adequate to consistently state whether or not left ventricular noncompaction changed over time or with therapy, as discussed in the “Limitations and Future Directions” section. The majority of patients' indications for echocardiography were to rule out structural heart disease or to evaluate a known cardiomyopathy. Many patients are referred to our institution for cardiomyopathy. Left ventricular noncompaction was an associated diagnosis that may not have been detected at the other institutions. As noted in the paper, one patient was discovered incidentally, prior to initiating chemotherapy.
Segmental Analysis
In all patients, the 16 segments were easily visualized and analyses were performed. Given that 16 segments were analyzed for 42 patients, a total of 672 segments were evaluated. In 150 of these segments, no left ventricular noncompaction was appreciated. One hundred ten segments lacked left ventricular noncompaction at the base. Only 30 segments lacked noncompaction at the midcavitary region, and only 10 lacked noncompaction at the apex.
High variability between adjacent regions was not as pronounced in our study. The most affected areas were the midpapillary and apical regions of the myocardium. The base was relatively spared, while the interventricular septum was not as affected as the free wall. This was explained in our “Discussion” section. Compaction begins at the base and extends to the apex; failure to compact would therefore affect the apex more than the base of the heart. Additionally, compaction occurs from the interventricular septum to the left ventricular free wall. Therefore, the free wall will be more affected than the interventricular septum.
Measurement
The papillary muscles and other parts of the mitral valve were deliberately excluded from the measurement of the noncompaction/compaction ratio. In our experience, the mitral valve apparatus can be differentiated from the regions of noncompaction, and therefore this was not an issue. Regions in which the mitral valve papillary muscles are present were deliberately avoided to limit measurement error and overestimation.
The ejection fraction by the method of disks is the better test to evaluate the function of the left ventricle in noncompaction when comparing with a shortening fraction by M-mode echocardiography. The reasons are clearly outlined in our article. In our experience, determining the noncompaction/compaction zone is necessary to outline a border. This border is used in diastole and systole to perform the ejection fraction calculation. The deep recesses and trabeculations were not traced for this purpose. In many adult patients, contrast echocardiography can be used to define the endocardial border, but we could not use such techniques given that this was a pediatric experience, and these agents are not approved for children. Instead, various other methods were used in our patient population. Higher frequency transducers can be used with special focus on the left ventricle, because pediatric patients are generally small. Limiting the depth and sector scan are effective methods to focus on the myocardium affected by left ventricular noncompaction.
Associated Pathology
After examining the data again, the patients with dilated cardiomyopathy had an average noncompaction/compaction ratio of 1.48 ± 0.28. Patients without dilated cardiomyopathy had an average noncompaction/compaction ratio of 1.20 ± 0.29. A t test with equal variances had a P value of .004, indicating a statistical difference between the groups. This particular analysis was not performed in our study. However, we reported more patients with cardiomyopathy in group 2 (patients who died or needed heart transplantation) than in group 1 (patients who neither died nor needed heart transplantation). Additionally, the patients in group 2 had more segments involved.
No obvious coronary anomalies were noted in the studied patients, except for patient 3 in group 2, who incidentally had a large left coronary artery. After reviewing the medical records, only patient 1 in group 1 had methylmalonic acidemia. There were no documented neuromuscular disorders or chromosomal abnormalities in the patients from our study.
We would like to thank Drs Stöllberger and Finsterer for their interest in our paper and for helping us clarify some residual issues.
References
- . Chromosomal abnormalities and neuromuscular disorders predict severity and outcome of noncompaction in addition to cardiac comorbidities. J Am Soc Echocardiogr. 2010;23:338
- . Cardiac segmental analysis in left ventricular noncompaction: experience in a pediatric population. J Am Soc Echocardiogr. 2010;23:46–53
- . Long-term follow-up of 34 adults with isolated left ventricular noncompaction: a distinct cardiomyopathy with poor prognosis. J Am Coll Cardiol. 2000;36:493–500
- . Echocardiographic and pathoanatomical characteristics of isolated left ventricular non-compaction: a step towards classification as a distinct cardiomyopathy. Heart. 2001;86:666–671
- Clinical features of isolated ventricular noncompaction in adults long-term clinical course, echocardiographic properties, and predictors of left ventricular failure. J Card Fail. 2006;12:726–733
PII: S0894-7317(10)00070-2
doi:10.1016/j.echo.2010.01.016
© 2010 American Society of Echocardiography. Published by Elsevier Inc. All rights reserved.
Refers to article:
- Chromosomal Abnormalities and Neuromuscular Disorders Predict Severity and Outcome of Noncompaction in Addition to Cardiac Comorbidities , 08 February 2010
Volume 23, Issue 3 , Pages 338-339, March 2010
