The value of T1 mapping in patients with chronic mitral regurgitation

Abstract

Listen

Translate article

Abstract Introduction The management of asymptomatic patients with severe mitral regurgitation (MR) and normal left ventricular (LV) ejection fraction (EF) remains controversial. Progressive fibrosis secondary to volume overload may explain irreversible LV dysfunction post mitral valve surgery, even in patients in which the current guidelines for intervention are applied. Considering the limitation of the LV EF as a measurement of systolic function, cardiac magnetic resonance emerges as a new technique that can detect and quantify left ventricular fibrosis before irreversible decline in LV function occurs. Late gadolinium enhancement (LGE) is a recognised method of assessing replacement fibrosis. Native T1 and post contrast administration T1 mapping provide a useful tool for measuring extracellular volume (ECV) – a marker of interstitial fibrosis. The purpose of this study was to assess the presence of myocardial fibrosis by LGE and T1 mapping in patients with moderate and severe mitral regurgitation and normal ejection fraction. Method The study group consisted of 128 consecutive patients with moderate and severe mitral regurgitation with no indication of surgery, compared with a control group of 120 patients with mild MR, studied between 2018 and 2021. Patients with contraindications to CMR were excluded. Electrocardiogram, transthoracic echocardiography and cardiac magnetic resonance, including LGE and T1 mapping were performed in all patients. Circle CVi 42 was used for image post processing and ECV calculation. Statistical analysis was performed with SPPSS 21.0. A p value <0.05 was considered statistically significant. Results 37 patients with MR presented with different nonischemic patterns of LGE versus 8 controls. Precontrast administration T1 mapping showed significantly higher global T1 time in patients with MR (1178±129 ms) versus controls (974±115). Mean ECV was significantly higher in patients with MR versus controls (36% vs 22%). A comparison between patients with moderate and severe MR revealed significantly higher T1 values and ECV in patients with severe MR despite normal LV EF. During the followup 15 patients required intervention. Conclusion Our study has shown that patients with moderate and severe MR that do not meet the current guidelines criteria for surgery have significantly higher T1 times and ECV compared with those with mild MR. The assessment of interstitial fibrosis using CMR T1 mapping techniques may provide an important tool in selecting patients who may benefit from early surgery before irreversible myocardial fibrotic changes occur, thus improving long term prognosis. Funding Acknowledgement Type of funding sources: None.