Dziadzko V, et al. - In a community-setting, experts coveted an investigation of the clinical characteristics, outcomes, and degree of undertreatment of mitral regurgitation. Findings disclosed that isolated mitral regurgitation was common and was related to excess mortality and frequent heart failure postdiagnosis in all patient subsets, even in those with normal left ventricular ejection fraction and low comorbidity. It was determined that only a minority of affected patients underwent mitral (or any type of cardiac) surgery even in a community with all means of diagnosis and treatment readily available and accessible regardless of the poor outcomes. This, in turn, pointed towards a possible, significant unmet need for treatment for this disorder in a wider cohort.

Methods

• Data from Mayo Clinic electronic health records and the Rochester Epidemiology Project were used to select all cases of moderate or severe isolated single-valvular mitral regurgitation (with no other severe left-sided valvular disease or previous mitral surgery) diagnosed during a 10-year period in the community setting in Olmsted County (MN, USA).
• An inspection was conducted of the clinical characteristics, mortality, heart failure incidence, and results of cardiac surgery post-diagnosis.

Results

• A total of 1,294 community residents (median age at diagnosis 77 years [IQR 66-84]) were diagnosed with moderate or severe mitral regurgitation by Doppler echocardiography (prevalence 0.46% [95% CI 0.42-0.49] overall; 0.59% [0.54-0.64] in adults) between Jan 1, 2000, and Dec 31, 2010.
• As per the outcomes, left-ventricular ejection fraction below 50% appeared to be frequent (recorded in 538 [42%] patients).
• Such patients presented with a slightly lower regurgitant volume compared to those with an ejection fraction of 50% or higher (mean 39 mL [SD 16] vs 45 mL [21], p < 0.0001).
• Data demonstrated that the post-diagnosis mortality was primarily cardiovascular in nature (in 420 [51%] of 824 patients for whom the cause of death was available) and higher than expected for residents of the county for age or sex (risk ratio [RR] 2.23 [95% CI 2.06-2.41], p < 0.0001).
• It was found that this excess mortality exerted an impact on all subsets of patients, whether they had a left-ventricular ejection fraction lower than 50% (RR 3.17 [95% CI 2.84-3.53], p < 0.0001) or of 50% or higher (1.71 [1.53-1.91], p < 0.0001) and with primary mitral regurgitation (RR 1.73 [95% CI 1.53-1.96], p < 0.0001) or secondary mitral regurgitation (2.72 [2.48-3.01], p < 0.0001).
• Researchers reported that even subjects with a low comorbidity burden combined with favourable characteristics such as left-ventricular ejection fraction of 50% or higher (RR 1.28 [95% CI 1.10-1.50], p < 0.0017) or primary mitral regurgitation (1.29 [1.09-1.52], p=0.0030) incurred excess mortality.
• Findings displayed that heart failure was frequent (mean 64% [SE 1] at 5 years postdiagnosis), even in patients with left-ventricular ejection fraction of 50% or higher (49% [2] at 5 years postdiagnosis) or in those with primary mitral regurgitation (48% [2]).
• In only 198 (15%) of 1,294 patients mitral surgery was ultimately performed, of which valve repair was the predominant type of surgery (in 149 [75%] patients).
• Herein, mitral surgery was done in 28 (5%) of 538 subjects with left-ventricular ejection fraction below 50% and in 170 (22%) of 756 patients with ejection fraction of 50% or higher, and in 34 (5%) of 723 with secondary mitral regurgitation compared to 164 (29%) of 571 with primary regurgitation.
• Compared to the number who underwent mitral surgery, all other types of cardiac surgery combined were performed in only 3% more patients (237 [18%] patients).