Patients with potentially fatal heart arrhythmias often benefit from receiving an implantable cardiac defibrillator (ICD) because of their high risk of sudden cardiac arrest.
The dilemma is figuring out who will benefit from the device.
Researchers suggest that positron emission tomography (PET) scan imaging may identify individuals at high risk of sudden cardiac arrest by detecting the loss of nerve function in the heart.
Principal investigator John M. Canty Jr., MD, the Albert and Elizabeth Rekate Professor of Medicine at the University of Buffalo School of Medicine and Biomedical Sciences and the university’s chief of cardiovascular medicine, said researchers hoped to identify a larger number of coronary artery disease patients at risk of sudden cardiac arrest.
Dr. Canty said the imaging may pinpoint individuals who could be candidates for an ICD in the future.
During the UB PAREPET study, or Prediction of Arrhythmic Events with Positron Emission Tomography, 204 advanced heart disease patients received a PET imaging scan.
Researchers examined the images for denervated myocardium, where sympathetic nerves in the heart have died or become damaged due to inadequate blood flow. This was measured by the heart’s ability to absorb a radioactive tracer injected into the patients.
Investigators found that there was a significant increase in the risk of sudden cardiac arrest when at least 38 percent of the heart nerves had become damaged or died.
Researchers had previously conducted pre-clinical studies with animals with ischemic heart disease, and also found that the risk of developing heart arrhythmias was related to denervation.
The current method for deciding who should receive an ICD involves measuring heart function by determining the percentage of blood pumped with each heartbeat.
When that percentage is less than 35 percent, patients are considered candidates because at that percentage, they are at high risk of sudden cardiac death.
The research, funded by the National Institutes of Health, was recently presented at the Heart Rhythm Society’s annual scientific sessions in Boston, Mass.
In the United States, over 850,000 people are hospitalized from an arrythmia, a general term for a large group of conditions that results from abnormal electrical activity in the heart. Also known as cardiac dysrhythmias, they can cause the heart to beat too fast, too slow, or in an irregular pattern.
The conditions can range from benign to life-threatening, and in some cases can cause sudden death. Common ‘palpitations’, such as premature ventricular contractions, may be simply uncomfortable and not need treatment, but others like atrial fibrillation need treatment because they increase the risk of stroke. In many cases, arrythmias will need treatment because they can lower blood pressure to the point that a patient can faint.