Cardiac MRI Quantification of MR to Identify The Patients For Surgery

The indication of surgery in severe mitral regurgitation is that when the patient becomes symptomatic and develops left ventricular dilatation or dysfunction.

Earlier intervention in asymptomatic individuals likely to ultimately need surgery may improve long-term prognosis, but identifying suitable patients for early surgery is difficult.

Cardiovascular magnetic resonance (CMR) can be used to accurately quantify MR, but is has not been studied as a means to identify patients who will be benefited by surgery.

Myerson et al compared the CMR quantification of MR and LV volume and function indexes for their relative predictive ability in 109 asymptomatic patients with at least moderate echocardiographic regurgitation who had baseline CMR scans and were followed for up to 8 years (mean, 2.5 years).

Standard CMR quantification of MR involves the deduction of aortic flow from LV stroke volume (aortic forward flow). In the absence of inter ventricular shunting, this equated to the volume of MR.

CMR quantification showed a strong ability to identify patients who ultimately progressed to symptoms or other indications for surgery:

• 91% of subjects with regurgitant volume ≤55 mL remained free of symptoms at 5 years without surger compared with only 21% with regurgitant volume >55 mL (p<0.0001).

A similar separation was observed for regurgitant fraction ≤40% and >40%. CMR-derived LV end-diastolic volume index showed a weaker association with outcome (proportions surviving without surgery at 5 years, 90% for <100 mL/m² versus 48% for ≥100 mL/m²) and added little to the discriminatory power of regurgitant fraction/volume alone, but was determined to be important for overall patient assessment.

In this study, CMR quantification of MR identified individuals likely to develop symptoms or other indications for surgery. CMR showed better discriminatory ability than the reference-standard CMR-derived LV volumes and may be able to identify appropriate patients for early surgery. Confirmation of this strategy in a randomized clinical trial is needed.

Reference

• 1 Myerson SG, d’Arcy J, Christiansen JP, et al (Neubauer S, senior author).Determination of clinical outcome in mitral regurgitation with cardiovascular magnetic resonance quantification. Circulation. 2016; 133: 2287-96.