NEW YORK (Reuters Health) - Glycogen-storage cardiomyopathy produced by certain genetic mutations can mimic hypertrophic cardiomyopathy, but the former usually shows electrophysiologic abnormalities, whereas the latter does not, new research indicates.
Unexplained left ventricular hypertrophy often leads to a diagnosis of hypertrophic cardiomyopathy, according to the report in The New England Journal of Medicine for January 27th. However, the new findings indicate that in about 4% of cases the disease is actually a glycogen-storage cardiomyopathy.
Distinguishing between these types of cardiomyopathy is important “because the long-term prognosis of each is different, which has a profound impact on how you manage the patient,” study co-author Dr. Christine E. Seidman, from Harvard Medical School in Boston, told Reuters Health.
For hypertrophic cardiomyopathy, which results from sarcomere-protein mutations, the prognosis is generally good and patients “can expect a long life span,” Dr. Seidmen noted.
In contrast, with glycogen-storage cardiomyopathy due to mutations in the AMP-activated protein kinase gamma2 (PRKAG2) gene, arrhythmias are common and pacemaker implantation is often required. Unfortunately, with the type caused by mutations in the lysosome-associated membrane 2 (LAMP2) gene, progression to heart failure occurs rapidly in early adulthood, often resulting in death.
The current study involved genetic analyses performed in 75 patients diagnosed with hypertrophic cardiomyopathy. An analysis of PRKAG2, LAMP2, and other genes involved in glycogen storage were performed in the 35 patients who had no sarcomere-protein mutations.
None of the patients had the genetic defects responsible for Fabry’s disease or Pompe’s disease, the authors note. In contrast, LAMP2 and PRKAG2 mutations were detected in a few patients, prompting the researchers to study two additional patient cohorts.
Among 20 patients with massive hypertrophy, but no electrophysiologic abnormalities, the authors found no LAMP2 or PRKAG2 mutations. In contrast, among 24 patients with increased left ventricular wall thickness and ECG evidence of ventricular preexcitation, four LAMP2 and seven PRKAG2 mutations were identified.
Features associated with the LAMP2 mutations included male gender, severe hypertrophy, onset between 8 and 17 years of age, ventricular preexcitation, and asymptomatic elevations of two serum proteins, the investigators note.
“ECG testing can help distinguish between the different types of cardiomyopathy, but I wouldn’t say it has the specificity” to make the diagnosis with complete certainty, Dr. Seidman noted. “Genetic analysis is really needed to determine the cause and guide management.”
Source: N Engl J Med 2005;352:362-372. [ Google search on this article ]
MeSH Headings:Diagnosis: Sarcomeres: Analytical, Diagnostic and Therapeutic Techniques and EquipmentCopyright © 2002 Reuters Limited. All rights reserved. Republication or redistribution of Reuters content, including by framing or similar means, is expressly prohibited without the prior written consent of Reuters. Reuters shall not be liable for any errors or delays in the content, or for any actions taken in reliance thereon. Reuters and the Reuters sphere logo are registered trademarks and trademarks of the Reuters group of companies around the world.
