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Utility of CMR in Aortic Regurgitation
Study Questions:
What is the diagnostic and prognostic value of cardiac magnetic resonance (CMR) imaging in chronic aortic regurgitation (AR)?
Methods:
The investigators analyzed 232 consecutive patients (34.5% were females 55.5 ± 19.8 years of age) with chronic AR (including 40 with moderate to severe and 44 with severe AR on echocardiography) who underwent CMR within 4 weeks of echocardiography. CMR included phase-contrast velocity-encoded imaging for the measurement of regurgitant volume and fraction at the sinotubular junction and assessment of holodiastolic retrograde flow (HRF) in the descending aorta. Significant AR was defined as the presence of HRF on CMR. Patients were followed prospectively, and multivariate Cox regression was applied for outcome analysis using a combination of heart failure, hospitalization, and cardiovascular death as primary endpoint.
Results:
AR severity on the basis of echo was reclassified in a significant number of patients according to CMR: 6.8% with mild AR on echo had HRF on CMR, whereas 34.1% with severe AR on echo did not have HRF on CMR and were reclassified as having nonsignificant AR. In 40 patients with uncertain AR severity (moderate to severe) on echo, 45.0% had HRF on CMR, indicating severe AR. Patients were followed for 35.3 ± 26.6 months. During that period, 63 patients (27.2%) reached the combined endpoint, including 43 (18.5%) with heart failure hospitalizations and 20 (8.6%) with cardiovascular deaths. By multivariate regression analysis, including clinical as well as imaging parameters, only N-terminal pro–B-type natriuretic peptide concentration (hazard ratio [HR], 2.184; 95% confidence interval [CI], 1.468-3.248; p < 0.001) and HRF on CMR (HR, 2.774; 95% CI, 1.131-6.802; p = 0.026) remained significantly associated with outcome.
Conclusions:
The authors concluded that in chronic AR, CMR has the potential to add important diagnostic and prognostic information.
Perspective:
This analysis reports that in a significant proportion of patients, AR severity as determined by echocardiography may be reclassified based on CMR assessment. Furthermore, holodiastolic retrograde flow on CMR was strongly and independently associated with event-free survival, defined as freedom from cardiac decompensation and death. CMR can easily and rapidly differentiate between severe and nonsevere AR, and should complement echocardiographic AR assessment in cases with limited examination quality or when difficult clinical decisions must be taken. Additional prospective trials investigating the utility of CMR for the optimal timing of surgery in patients with AR are indicated.
Clinical Topics: Anticoagulation Management, Heart Failure and Cardiomyopathies, Noninvasive Imaging, Valvular Heart Disease, Acute Heart Failure, Heart Failure and Cardiac Biomarkers, Echocardiography/Ultrasound, Magnetic Resonance Imaging
Keywords: Aorta, Thoracic, Aortic Valve Insufficiency, Diagnostic Imaging, Echocardiography, Heart Failure, Magnetic Resonance Imaging, Magnetic Resonance Spectroscopy, Natriuretic Peptide, Brain, Peptide Fragments
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