"If the molecular imaging techniques are used for appropriate selection of ICD candidates, not only overuse but also underuse of ICD could be avoided and the assessment may be shown to be more cost-effective,” said Kimio Nishisato, M.D., a physician in the cardiology division of Muroram City General Hospital (Japan), and corresponding author for the study.

According to researchers from Sapporo University (Japan), the study revealed that molecular imaging could play a key role in diagnosing and guiding the treatment strategy for arrhythmia, coronary artery disease, and heart failure. "This research holds significant potential for the detection, diagnosis, and treatment of many common cardiovascular conditions,” said Tomoaki Nakata, M.D., Ph.D., an associate professor at the Sapporo Medical University School of Medicine and director of the Hokkaido Prefectural Esashi Hospital, Japan. "With molecular imaging, physicians can improve patient care by pinpointing the precise location of the disease in order to eliminate the need for invasive medical devices and unnecessary surgical techniques.” Dr. Nakata added that molecular imaging can also decrease unnecessary medical costs by better targeting treatment for each individual patient.

In this study, published in the August 2010 issue of the Journal of Nuclear Medicine (JNM), researchers theorized that both the impairment of myocardial perfusion and/or cell viability and cardiac sympathetic innervations are responsible for heart arrhythmia and sudden cardiac death. However, there was no established effective technique, including a molecular imaging technique, which is highly objective, reproducible, and quantitative.

The researchers studied the prognostic implications of cardiac pre-synaptic sympathetic function quantified by cardiac metaiodobenzylguanidine (MIBG) activity and myocyte damage or viability quantified by cardiac tetrofosmin activity in patients treated with prophylactic use of ICD, by correlating with lethal arrhythmic events that would have been documented during a prospective follow-up. Based on these features, the study is the first to show the efficacies of the method for more accurate identification of patients at greater risk of lethal arrhythmias and sudden cardiac death (SCD).

"Sudden cardiac death due to lethal arrhythmia represents an important healthcare problem in many developed countries,” said Ichiro Matsunari, M.D., Ph.D., director of the clinical research department at the Medical & Pharmacological Research Center Foundation (Hakui, Japan) and author of an invited perspective also published in the August 2010 JNM. "While implantable cardioverter defibrillator therapy is an effective option over anti-arrhythmic medications to prevent SCD, the balance of clinical benefits, efficacy, and risks is still a matter of discussion.”

Dr. Matsunari added that better, more precise strategies such as the molecular imaging technique used in this study are needed to identify high-risk patients for SCD, who are most likely to benefit from ICD therapy. SCD is frequently the first manifestation of an underlying disease--but one that current treatments such as ICD cannot always detect. Molecular imaging helps guide diagnosis and treatment as well as helps avoid unnecessary ICD treatment.