Mitral Annulus Calcification Can Predict Increased Risk of Mortality, Mitral Valve Dysfunction

Patricia Pellikka, MD

New research suggests mitral annulus calcification (MAC) could serve as a predictor of increased mortality risk in patients, regardless of whether or not they went on to experience mitral valve dysfunction (MVD).

A retrospective review of data from more than 24,000 patients evaluated with an EKG by Mayo Clinic clinicians, results of the study indicated MAC was common, present in 23% of patients, and was associated with a doubling in the risk of MVD as well as increased risk of mortality, regardless if patients had MVD or not.

"The association between mitral annulus calcification and mitral valve dysfunction is important to understand because it affects treatment considerations for valve dysfunction," said study investigator Patricia Pellikka, MD, cardiologist at Mayo Clinic, in a press release from the Mayo Clinic. "Mitral valve surgery is associated with high risk for patients with mitral annulus calcification, in part because advanced age can be a factor. Severe calcification makes mitral valve procedures more challenging to perform. Our study aimed to assess the characteristics and risk factors of mitral annulus calcification, and the prognostic impact of associations with mitral valve dysfunction."

With support through a grant from Abbott Structural Heart, Pellikka and a team of colleagues from the Mayo Clinic sought to develop a greater understanding of the prevalence and prognostic value of MAC. With this in mind, investigators designed the study as a retrospective review of all adults who underwent transthoracic echocardiography at the Mayo Clinic in Rochester, Minnesota between January 1 and December 31, 2015.

The primary outcome of interest for the study was all-cause mortality. Investigators pointed out patients were censored at the date of mitral valve intervention for both patients with and without MAC in subgroups analyses to assess mortality without mitral valve intervention. For the purpose of analysis, MVD was defined as mitral regurgitation or mitral stenosis of moderate or greeter severity.

During 2015, a total of 24,414 patients underwent evaluation with echocardiography at Mayo Clinic in Rochester, Minnesota. Of these, 23% (n=5502) had MAC. Compared to those without MAC, patients with MAC were older (75±10 vs 60±16 years; P <.01) and the prevalence of MAC approved to increase with age. Of the 5502 with MAC, 16% (n=881) experienced MVD. Among those with MAC, those with MVD were more often women (54% vs 44%; P <.01) and more frequently frail (52% vs 44%; P <.01). Investigators pointed out aortic valve dysfunction, female sex, chest irradiation, renal dysfunction, and coronary artery disease were all associated with mitral stenosis among patients with MAC.

Initial analysis indicated the Kaplan-Meier 1-year survival was 76% among those with MAC and MVD, 87% among those with MAC but no MVD, 86% in those without MAC but with MVD, and 92% in those with no MAC and no MVD. After adjustment for multiple factors, including age, diabetes, renal dysfunction, cancer, chest irradiation, ejection fraction below 50%, aortic stenosis, tricuspid regurgitation, and pulmonary hypertension, MAC was associated with greater risk of mortality (aHR, 1.40 [95% CI, 1.31-1.49]; P <.001).

When assessing risk with MVD, results indicated MVD was associated with an additional increase in mortality among patients MAC (aHR, 1.79 [95% CI, 1.58-2.01]; P <.001). Investigators pointed out there was no significant interaction observed between MAC and MVD for mortality (P=.10).

"Mitral annulus calcification has been known to be associated with cardiovascular disease and mortality, but we did not previously appreciate the strength of this relationship even after adjustment for multiple clinical and echocardiographic variables," Pellikka added. "Patients with calcification more commonly had not only mitral valve dysfunction, but also aortic valve disease. For clinicians, suspicion for valve diseases should be increased and evaluations carefully performed for patients with mitral annulus calcification.

This study, “Prevalence and Natural History of Mitral Annulus Calcification and Related Valve Dysfunction,” was published in Mayo Clinic Proceedings.