Myocardial External Efficiency in Asymptomatic Severe Primary Mitral Regurgitation Using 11C-Acetate PET

• Subjects with asymptomatic moderate-severe or severe primary mitral regurgitation (MR) are closely observed for signs of progression or symptoms requiring surgical intervention. The role of myocardial metabolic function in progression of MR is poorly understood. We used 11C-acetate positron emission tomography (PET) to non-invasively measure myocardial external efficiency (MEE), which is the energetic ratio of external cardiac work and left ventricular oxygen consumption.Methods and Results: 47 patients in surveillance with MR and no or minimal symptoms prospectively underwent PET, echocardiography and cardiac magnetic resonance imaging (CMR) on the same day. PET was used to simultaneously measure cardiac output, LV mass and oxygen consumption to establish MEE. PET in patients were compared to healthy volunteers (n = 9). MEE and standard imaging indicators of regurgitation severity, LV volumes and function were studied as predictors of time to surgical intervention. Patients were followed median 3.0 years (interquartile range 2.0-3.8) and the endpoint was reached in 22 subjects (47%). MEE in patients reaching the endpoint (23.8±5.0%) was lower than in censored patients (28.5±4.5%, P = 0.002) and in healthy volunteers (30.1±4.9%, 0.001). MEE with a cut-off lower than 25.7% was significantly associated with the outcome (hazard ratio of 7.5 (95%CI: 2.7-20.6, p<0.0001) and retained independent significance when compared to standard imaging parameters.Conclusion: MEE independently predicted time to progression requiring valve surgery in patients with asymptomatic moderate-severe or severe primary MR. The study suggests that inefficient myocardial oxidative metabolism precedes clinically observed progression in MR.

Ämnesord

MEDICIN OCH HÄLSOVETENSKAP  -- Klinisk medicin -- Kardiologi (hsv//swe)

MEDICAL AND HEALTH SCIENCES  -- Clinical Medicine -- Cardiac and Cardiovascular Systems (hsv//eng)

MEDICIN OCH HÄLSOVETENSKAP  -- Klinisk medicin -- Radiologi och bildbehandling (hsv//swe)

MEDICAL AND HEALTH SCIENCES  -- Clinical Medicine -- Radiology, Nuclear Medicine and Medical Imaging (hsv//eng)

Nyckelord

myocardial efficiency

efficiencymitral regurgitation

cardiovascular MR

PET

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