The relationship between symptoms and regurgitant severity in primary mitral regurgitation: a cardiovascular magnetic resonance study

In the ACC/AHA guidelines, the presence of symptoms plays a central role in determining timing surgery in primary mitral regurgitation (MR). Studies have shown a disconnect between the severity of MR and symptoms. The purpose of this study is to assess risk factors for symptoms in patients with chronic primary MR. There were 430 patients with degenerative MR and preserved left ventricular function who underwent cardiovascular magnetic resonance (CMR). MR volume (MRV) and MR fraction (MRF) were categorized as per the ACC/AHA guidelines. Patients were divided into three groups based on category of MRV and MRF: (1) MRV category > MRF category (V > F), (2) MRV = MRF category (V = F), and (3) MRV < MRF category (V < F). Symptoms were defined as shortness of breath, fatigue, and decreased exercise capacity and extracted from chart review. There were 134 (38%) patients who reported symptoms. Based on MRV, 236 (55%), 125 (29%), and 69 (16%) patients had mild moderate, and severe MR respectively. Based on MRF, 257 (60%), 130 (30%), and 43 (10%) patients had mild moderate, and severe MR respectively. There was no increase in the prevalence of symptoms with worsening MRV severity (39%, 40% and 30% for mild, moderate and severe MRV respectively, p = 0.4). There was a trend for increase in the prevalence of symptoms in patients with severe MRF (35%, 40% and 54% for mild, moderate and severe MRF respectively, p = 0.054). There was a significant increase in the prevalence of symptoms when comparing V > F, V = F, and V < F (20%, 40%, and 72% respectively, p < 0.0001). On multivariable analysis, risk factors for symptoms were age, female sex, MRF, and having a V < F. In patients undergoing CMR with degenerative MR the prevalence of symptoms do not increase with worsening MRV. MRV and MRF were not risk factors for symptoms but having V < F was a risk factors for the presence of symptoms. These findings suggest that symptomatic patients with MR may have other pathology which may be responsible for their symptoms. Further studies are needed to better characterize the relationship between MR severity and symptoms.