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Stress Myocardial Perfusion Imaging by Cardiac Magnetic Resonance Provides Strong Prognostic Value to Cardiac Events Regardless of Patient’s Sex
Study Questions:
What are the prognostic implications of vasodilator stress cardiac magnetic resonance (CMR) imaging in men and women?
Methods:
Vasodilator stress CMR was performed in 424 consecutive patients who were subsequently followed for major adverse cardiac events (MACE), defined as cardiac death or new acute myocardial infarction (AMI). CMR perfusion was graded on a 17-segment model as 0 = no defect; 1 = ≤50% defect; and 2 = ≥50% defect, from which an ischemia score was calculated. Late gadolinium enhancement (LGE) was also quantified. A clinical score was also calculated, which included multiple patient demographics and ECG variables.
Results:
Nineteen patients were excluded from study analysis for a variety of reasons, leaving 405 in the study cohort. Clinical follow-up was available for 6 months to 6.9 years (median 30 months). Average patient age was 57 ± 14 years and was not statistically different comparing the 168 women to the 237 men. Similarly, there was no difference between men and women in the prevalence of hypertension, diabetes, tobacco use, or clinical score. Prior myocardial infarction was present in 14% of women and 25% of men (p < 0.0001). Resting regional wall motion abnormalities were more prevalent in men than women (32.5% vs. 15%) as was presence of LGE (13% vs. 41%; both p < 0.0001). Ischemia was present in 31% of men compared to 21% of women, and the ischemic score was 0.9 ± 2.2 versus 1.6 ± 3.5, respectively (both p < 0.05). On follow-up, MACE occurred in 36 patients (9%), including 21 cardiac deaths and 15 acute myocardial infarctions. MACE occurred in 14 women and 22 men. For both men and women, univariable predictors of MACE included age, history of hypertension, clinical score, left ventricular ejection fraction, resting regional wall motion abnormalities, presence of LGE, presence of ischemia, and ischemia score. Considering all patients, the best multivariable model for prediction of MACE included ischemia score, presence of ischemia, and clinical score (chi-square 68.67). For women, the best multivariable model included ischemia score and need for early revascularization (chi-square 37.7), and for men, ischemia score plus clinical score (chi-square 30.1). Annual event rates for MACE were 1.1% in men and 0.3% in women in the absence of ischemia, and 10.8% and 15.1% for ischemia. Kaplan-Meier survival curves demonstrated that ischemia was associated with reduced MACE-free survival and cardiac survival for both men and women.
Conclusions:
Stress myocardial perfusion imaging with CMR provides prognostic information for subsequent cardiac events in both men and women. A perfusion CMR without evidence of myocardial ischemia indicates a very low risk of subsequent MACE in men and women.
Perspective:
Stress perfusion imaging with CMR has previously been demonstrated to be an accurate method for detection of obstructive coronary artery disease. This study expands the observation to prognostic implications. The role and validity of various forms of cardiovascular stress testing in women have often been disputed, with a well-described higher prevalence of false-positive studies of women using electrocardiogram analysis alone. Imaging techniques such as stress echocardiography and myocardial perfusion imaging have largely mitigated this difference. This study nicely demonstrates that perfusion imaging with CMR provides equivalent prognostic information in men and women. This study also confirms a very low event rate following perfusion CMR, which was free of inducible ischemia, providing an excellent negative predictive value for subsequent hard cardiac events over a follow-up extending as long as 6.9 years.
Keywords: Myocardial Perfusion Imaging, Coronary Artery Disease, Myocardial Ischemia, Myocardial Infarction, Follow-Up Studies, Echocardiography, Stress, Electrocardiography, Magnetic Resonance Imaging, Vasodilator Agents, Perfusion Imaging, Prevalence, Prognosis, Cardiovascular Diseases, Magnetic Resonance Spectroscopy, Hypertension, Exercise Test
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