Prognostic value of global MR myocardial perfusion imaging in women with suspected myocardial ischemia and no obstructive coronary disease: results from the NHLBI-sponsored WISE (Women's Ischemia Syndrome Evaluation) study

Abstract

Objectives: The purpose of this study was to assess the prognostic value of global magnetic resonance (MR) myocardial perfusion imaging (MPI) in women with suspected myocardial ischemia and no obstructive (stenosis <50%) coronary artery disease (CAD).

Background: The prognostic value of global MR-MPI in women without obstructive CAD remains unknown.

Methods: Women (n = 100, mean age 57 ± 11 years, age range 31 to 76 years), with symptoms of myocardial ischemia and with no obstructive CAD, as assessed by coronary angiography, underwent MR-MPI and standard functional assessment. During follow-up (34 ± 16 months), time to first adverse event (death, myocardial infarction, or hospitalization for worsening anginal symptoms) was analyzed using global MPI and left ventricular ejection fraction (EF) data.

Results: Adverse events occurred in 23 (23%) women. Using univariable Cox proportional hazards regression modeling, variables found to be predictive of adverse events were global MR-MPI average uptake slope (p < 0.05), the ratio of MR-MPI peak signal amplitude to uptake slope (p < 0.05), and EF (p < 0.05). Two multivariable Cox models were formed, 1 using variables that were performance site dependent: ratio of MR-MPI peak amplitude to uptake slope together with EF (chi square: 13, p < 0.005); and a model using variables that were performance site independent: MR-MPI slope and EF (chi square: 12, p < 0.005). Each of the 2 multivariable models remained predictive of adverse events after adjustment for age, disease history, and Framingham risk score. For each of the Cox models, patients were categorized as high risk if they were in the upper quartile of the model and as not high risk otherwise. Kaplan-Meier analysis of time to event was performed for high risk versus not high risk for site-dependent (log rank: 15.2, p < 0.001) and site-independent (log rank: 13.0, p < 001) models.

Conclusions: Among women with suspected myocardial ischemia and no obstructive CAD, MR-MPI-determined global measurements of normalized uptake slope and peak signal uptake, together with global functional assessment of EF, appear to predict prognosis.

Figure 1

Magnetic resonance (MR) myocardial perfusion image (MPI) analysis, for, top panel, a patient with a low average MPI level and, lower panel, for a patient with a high average MPI level. Six myocardial regions and a left ventricular blood pool region are drawn on one frame (lower inset). Extracted and parameterized intensity-time curves are shown in the right-hand display section for the left ventricular blood pool (highest peak) and each of six myocardial sections (closely grouped uptake curves). In these patients no perfusion defects or obstructive stenoses were present, while the patient with low MPI subsequently died and the patient with high MPI survived event free.

Figure 2

Kaplan-Meier cumulative event-free survival curves for adverse events (p<0.005) in high-risk and not high-risk patients stratified by highest quartile of Cox model incorporating the ratio of MR-MPI average amplitude to normalized uptake slope and ejection fraction.