Cardiac MR Provides Clues on Little Known Heart Muscle Condition

Left ventricular noncompaction (LVNC), a cardiomyopathy about which little is fully understood is associated with heart failure (HF), stroke, and ventricular arrhythmias, according to recent findings. The researchers reported that sophisticated imaging technologies reveal that developing these cardiac risks appear to progress over time in patients with LVNC.

LVNC is an inherited heart muscle condition in which the muscular wall of the left ventricle appears to be spongy and noncompacted, consisting of a meshwork of numerous muscle bands (trabeculations). However, its cause, development, clinical course, and treatment are the focus of ongoing research. As a result, the study investigators reported that the cardiology community's "understanding of the natural history of LVNC continues to evolve.”

The study's findings were presented November 2010 at the 2010 American Heart Association (AHA) scientific sessions in Chicago, IL, USA. "Our ability to detect and recognize this condition has grown considerably over the past decade, as our imaging technologies have advanced,” said study investigator William T. Katsiyiannis, MD, director of the Genetic Arrhythmia Center and a clinical cardiac electrophysiologist at the Minneapolis Heart Institute at Abbott Northwestern Hospital (Minneapolis, USA). "Fifteen years ago, the main tool to examine cardiac muscle was echocardiography, which was not as sensitive as it is today. Now, with the advent of cardiac MR [magnetic resonance], we are able to see far more detail of the heart.”

Whereas the current incidence rate of LVNC is unknown, Dr. Katsiyiannis theorized that the condition might be far more common than has been previously postulated, due to a lack of diagnosis. Earlier research had indicated complications for patients with LVNC include stroke from blood clots that form in the noncompacted tissue, the development of heart failure or left ventricular dysfunction, and the development of potentially dangerous ventricular arrhythmias.

To evaluate the association of LVNC with these traditional risk factors, the researchers assessed patients by echocardiography or cardiac MR, and diagnosed 125 patients with LVNC. Only 38.2% were diagnosed by echocardiography. "The incidence rates are unclear because echo has been the gold standard,” stated Dr. Katsiyiannis. "Echo missed the majority of patients with LVNC. Therefore, LVNC cannot be ruled out based on a normal echo.”

The study's patients had a higher than expected incidence of congestive heart failure (38.5%), left ventricular dysfunction with ejection fraction of less than 45% by cardiac MR (31.9%), and ventricular tachycardia (24.8%). Moreover, the researchers at the Minneapolis Heart Institute reported that 3.1% of patients experienced stroke and 3.1% experienced sudden death.

Dr. Katsiyiannis concluded that LVNC requires "much more research before clinical decisions are based on its diagnosis.”

Related Links:
Minneapolis Heart Institute at Abbott Northwestern Hospital