JACC: SPECT perfusion imaging predicts death in women

SPECT myocardial perfusion imaging with technetium-99m (Tc99m) shows normal findings. Source: Daniel S. Berman, MD, director of cardiac imaging and nuclear cardiology at Cedars-Sinai Heart Institute

SPECT myocardial perfusion imaging (MPI) can detect risk of death in women, according to a study published in the August issue of the Journal of the American College of Cardiology: Cardiovascular Imaging. A study of nearly 2,500 Brazilian women showed that adding SPECT MPI to the care spectrum enhanced prognostic information regarding myocardial perfusion and left ventricular ejection fraction (LVEF).

“Interest and emphasis on research concerning women and heart disease has grown substantially with increasing recognition of the importance of heart disease related to the female sex,” Mario Sergio Julio Cerci, MD, MPH, of the Quanta Diagnóstico Nuclear in Curitiba, Brazil, and colleagues wrote. “However, a concerning gap in the knowledge, understanding and general awareness of ischemic heart disease (IHD) in women still remains.”

During the study, Julio Cerci and colleagues set out to better understand the prognostic value of SPECT-MPI in women; all-cause mortality was the primary outcome used. The study population consisted of 2,225 female patients between the ages of 55 and 75 years old who underwent SPECT-MPI between March 2004 and October 2007.

Patients underwent stress and rest imaging studies after an intravenous injection of 20 to 25 mCi of 99m Tc-sestamibi. The protocol used had an effective dose near 10 mSv. Patients had an average LVEF of 64.4 percent and 20.2 percent of the patients had a previous history of ischemic heart disease. Of the patients, 73.1 percent underwent a treadmill stress test and 26.9 percent underwent pharmacological stress testing.

During the 3.7 year follow-up period, 139 patients died and the event rate was 6.2 percent. After the researchers adjusted for ischemic heart disease risk factors and LVEF, they reported that the presence of any perfusion defect was an independent predictor of mortality. A univariate analysis showed that ischemic heart disease and older age were the only clinical variables for the prediction of death. Additionally, a lower LVEF and presence of any perfusion defect were high predictors of death.

The researchers also reported that patients with abnormal scans had a higher rate of death compared with those who had normal scans, 13.1 percent vs. 4 percent.

“[T]he presence of myocardial perfusion defect was incremental and led to a more refined estimation of mortality risk. An important strength of a diagnostic test is the number of patients identified as having higher and lower risk and, consequently, becoming eligible or not to receive different therapy (usually more intensive and expensive),” the authors wrote.

During the study the researchers noted that 54 percent of adverse events occurred in patients deemed as high risk and 73 percent occurred in patients classified as low or intermediate risk. Nearly 8 percent of the patients were reclassified as high risk and 10.6 percent as low risk with SPECT MPI.

“With the new paradigms where MPI may be used to guide IHD patient decision-making regarding target intervention or clinical treatment, the prognostic implication of different types and severity of perfusion defects must be completely defined in the previously underrepresented female population,” the authors concluded. “SPECT-MPI added significant incremental prognostic information to clinical and left ventricular functional variables.”