Mitral Annular Calcification in Patients Undergoing TAVR
What are the prevalence and clinical implications of mitral annular calcification (MAC) among patients with severe aortic stenosis (AS) during and following transcatheter aortic valve replacement (TAVR)?
In a retrospective study that examined 761 patients with severe symptomatic AS who underwent TAVR during a 3-year period at a single center, consecutive patients were compared based on the existence and severity of MAC on pre-TAVR computed tomography (CT) scans. MAC severity was qualitatively assessed by the circumferential involvement of the mitral ring: less than one-third of the annulus involved (mild MAC); between one-third and one-half (moderate); and calcification in greater than one-half of the mitral annulus circumference (severe).
From the entire cohort of 761 patients, 49.3% had MAC, and 50.7% did not have MAC. Mild MAC was present in 231 patients (30.4%), moderate MAC in 72 patients (9.5%), and severe MAC in 72 patients (9.5%). At 30 days, mortality and major complications were similar between patients with and without MAC. In a multivariable survival analysis, severe MAC was found to be an independent strong predictor of overall mortality following TAVR (all-cause mortality hazard ratio [HR], 1.95; 95% confidence interval [CI], 1.24-3.07; p = 0.004; cardiovascular mortality HR, 2.35; 95% CI, 1.19–4.66; p = 0.01). Severe MAC also was found to be an independent strong predictor of new permanent pacemaker implantation after TAVR (odds ratio, 2.83; 95% CI, 1.08-7.47; p = 0.03).
One-half of patients with severe AS evaluated for TAVR were found to have MAC. The authors concluded that severe MAC is associated with increased all-cause and cardiovascular mortality and with conduction abnormalities following TAVR, and should be included in future risk stratification models for TAVR.
Calcified AS and MAC might have similar etiological and pathophysiological mechanisms, and MAC frequently is encountered on preprocedural echocardiographic and CT imaging among patients undergoing evaluation for TAVR. This study found a correlation between the presence of “severe” MAC on CT (MAC involving greater than one-half of the mitral annular circumference) and increased 30-day all-cause and cardiovascular mortality, and with conduction abnormalities leading to pacemaker implantation following TAVR.
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