AHA: Cardiac MR helps outline risks for left ventricular non-compaction

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Researchers have found that cardiac MR diagnoses significantly more patients with left ventricular non-compaction, a cardiomyopathy that is associated with heart failure, stroke and ventricular arrhythmias, than echocardiography. They suggest the condition may be under-reported because of echo's lower sensitivity.

Henri Roukoz, MD, from the University of Minnesota, and colleagues presented the scientific poster at the 2010 American Heart Association (AHA) Scientific Sessions in Chicago.

Left ventricular non-compaction (LVNC) is an inherited heart muscle condition in which the muscular wall of the LV appears to be spongy and non-compacted, consisting of a meshwork of numerous muscle bands. However, its cause, development, clinical course and treatment are the focus of ongoing research.

"Our ability to detect and recognize this condition has grown considerably over the past decade, as our imaging technologies have advanced," said coauthor William T. Katsiyiannis, MD, director of the Genetic Arrhythmia Center and a clinical cardiac electrophysiologist at the Minneapolis Heart Institute at Abbott Northwestern Hospital in Minneapolis. "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, we are able to see far more detail of the heart."

While the current incidence rate of LVNC is unknown, Katsiyiannis hypothesized that the condition may be far more common than has been previously postulated, due to a lack of diagnosis.

Previous data have indicated complications for patients with LVNC include stroke from blood clots that form in the non-compacted tissue, the development of heart failure or LV dysfunction and the development of potentially dangerous ventricular arrhythmias.

To assess the association of LVNC with these traditional risk factors, the researchers identified 125 patients diagnosed by cardiac MR with LVNC. Echocardiography diagnosed only 38.2 percent of these patients.

"The incidence rates are unclear because echo has been the gold standard," said Katsiyiannis. "Echo missed the majority of patients with LVNC. Therefore, LVNC cannot be ruled out based on a normal echo."

The study's patient population had a higher than expected incidence of congestive heart failure (38.5 percent), LV dysfunction with ejection fraction (EF) of less than 45 percent by cardiac MR (31.9 percent) and ventricular tachycardia (24.8 percent).

In addition, the researchers reported that 3.1 percent of patients experienced stroke and 3.1 percent experienced sudden death.

Overall, the researchers found that:
  • LVNC is associated with increased risk of chronic heart failure (CHF). Risk factors include female gender and family history of CHF.
  • LVNC is associated with ventricular arrhythmias. Risk factors include family history of sudden cardiac death and any LV dysfunction.
  • Three patients presented with sudden cardiac death, none had diabetes, hypertension or hyperlipidemia; however, EF less than 45 percent was a factor: odds ratio (OR) was 9.37.
  • Three patients had stroke/transient ischemic attack. All were female and had hypertension and hyperlipidemia. LV dysfunction was not associated with these: For EF less than 45 percent: OR was 1.0.

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