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Cardiac Remodeling in Left-Sided Valvular Regurgitation
Quick Takes
- In this cohort study including 418 patients with aortic regurgitation (AR) and 1,073 with mitral regurgitation (MR), AR resulted in more profound left ventricular remodeling than MR.
- Among CMR parameters, aortic regurgitant volume and regurgitant fraction had the best discriminatory power for clinically indicated aortic valve replacement (AVR). The traditional regurgitant volume and fraction cutoffs for severe AR (60 mL and 50%, respectively) were highly specific but poorly sensitive for identifying clinical indications for AVR.
Study Questions:
How does left ventricular (LV) remodeling differ in patients with chronic aortic regurgitation (AR), as compared with chronic mitral regurgitation (MR)? In chronic AR, how does left ventricular (LV) remodeling correlate with aortic valve replacement (AVR)?
Methods:
This single-center, registry-based study included consecutive patients who underwent clinical cardiovascular magnetic resonance (CMR) from 2008–2018. Notable exclusion criteria were LV ejection fraction (LVEF) <50%, greater than mild aortic stenosis, and late gadolinium enhancement (LGE) involving >5% of the myocardium in an ischemic pattern. Patients with chronic AR were followed until AVR, death, or end of the study period. The primary outcome was AVR.
Results:
The cohort comprised 1,491 patients, including 418 with isolated AR and 1,073 with isolated MR. The AR group included more men (66.7% vs. 48.3% of MR patients) and more patients with hypertension (67.2% vs. 58.7%). Among patients with moderate or greater regurgitation (regurgitant fraction ≥31%), patients with AR had larger LV volumes and diameters as compared with MR patients, despite adjustment for baseline characteristics. As AR severity progressed, LVEF gradually declined. As MR severity progressed, LVEF initially increased, then declined.
Of the 390 patients with AR who had follow-up after CMR (median follow-up period 2.1 years), 73 (18.7%) underwent AVR, and 12 patients (3.1%) died. The primary indication for AVR was symptomatic heart failure in 40 patients, LV remodeling in 6 patients, and a combination of symptoms and LV remodeling in 27 patients. In receiver operating characteristic analyses, aortic regurgitant volume and regurgitant fraction had the best discriminatory power for AVR (areas under the curve [AUC] 0.95 and 0.94, and optimal cutoffs 38 mL and 35%, respectively), outperforming other parameters including LV end-diastolic volume index (AUC 0.85) and LV end-systolic diameter (AUC 0.79). The traditional regurgitant volume and fraction cutoffs for severe AR (60 mL and 50%, respectively) were highly specific (98.1% and 99.1%) but poorly sensitive (53.4% and 24.7%) for identifying clinical indications for AVR. Based on these findings, the authors propose a revised regurgitant fraction cutoff of ≥40% for severe AR.
Conclusions:
Among patients with moderate or greater AR, the degree of LV remodeling observed is greater than that with moderate or greater MR. Patients with significant AR often become symptomatic and undergo AVR before meeting traditional quantitative imaging criteria for surgical intervention.
Perspective:
Many patients in this study underwent AVR for symptoms before they met traditional LV remodeling cutoffs for surgery, highlighting the importance of close clinical follow-up for patients with moderate or severe AR. In everyday practice, most patients with AR are followed with echocardiography, though precise AR quantification can be very challenging with this workhorse imaging modality. Particularly for patients who have borderline or inconclusive echocardiographic findings, CMR should be employed to clarify AR severity and quantify LV volumes and systolic function. A limitation of this study is that patients did not undergo exercise testing, which is invaluable for quantifying exercise tolerance objectively and providing serial assessments of exercise capacity over time.
Clinical Topics: Cardiac Surgery, Heart Failure and Cardiomyopathies, Invasive Cardiovascular Angiography and Intervention, Noninvasive Imaging, Prevention, Valvular Heart Disease, Aortic Surgery, Cardiac Surgery and Heart Failure, Cardiac Surgery and VHD, Acute Heart Failure, Interventions and Imaging, Interventions and Structural Heart Disease, Echocardiography/Ultrasound, Magnetic Resonance Imaging, Hypertension, Mitral Regurgitation
Keywords: Aortic Valve Insufficiency, Aortic Valve Stenosis, Cardiac Surgical Procedures, Contrast Media, Diagnostic Imaging, Echocardiography, Exercise Tolerance, Gadolinium, Heart Failure, Heart Valve Diseases, Hypertension, Magnetic Resonance Imaging, Mitral Valve Insufficiency, Myocardium, Stroke Volume, Transcatheter Aortic Valve Replacement, Ventricular Remodeling
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