The combination of two different types of imaging seems to be the most accurate way to predict heart attacks. Based on studies from the University Hospital Zurich in Switzerland, a hybrid diagnostic approach is necessary to identify which coronary artery disease (CAD) patients are at the highest risk of heart attack and other dangerous “adverse cardiac events” (ACEs).
CAD is the leading cause of death for men and women worldwide and the most common type of heart disease. This condition occurs when arteries that supply blood to the heart become hardened and narrowed when plaque builds up inside, a condition called atherosclerosis. When the blood supply to the heart is completely cut off (ischemia), a person has a heart attack, which causes heart muscle cells to die.
People with CAD may undergo a diagnostic test called invasive coronary angiography (ICA) for doctors to assess the progression of artery blockage in CAD (stenosis). But researchers from the new study pointed out that this diagnostic approach is missing a measurement of how much blood is able to flow into the heart (perfusion) when the coronary arteries are blocked by plaque buildup.
"In lesions with less than 50 percent narrowing, one in five lesions still produce an ischemia," said study co-author Philipp A. Kaufmann, MD. A hybrid option that includes diagnostic testing of both stenosis and perfusion could provide data to predict the risk of heart attack in the long-term, helping doctors make treatment plans.
The new study followed 428 patients for about seven years. All of the participants had cardiac hybrid imaging done, which included both “coronary computed tomography angiography” (CCTA) and “myocardial perfusion imaging” with “single photon emission computed tomography” (SPECT).
At the end of the study, there were 160 ACEs, including 45 deaths. Patients whose diagnostic results showed progressive signs of CAD in the context of both stenosis and perfusion were five times more likely to have an ACE than those who had normal results. Patients with progressive stenosis or perfusion but not both had three times the risk of those with normal results.
"In a previous multicenter trial, with hybrid imaging we were able to see that about one in five patients should be revascularized in another coronary artery than originally planned,” Kaufmann explained. “The present study now documents the prognostic importance of the comprehensive assessment provided by hybrid imaging."
Coming up next could be triple hybrid imaging, combining the CCTA/SPECT hybrid with a diagnostic test that measures coronary artery shear stress.
The present study was published in the journal Radiology.