Multimorbidity is strongly associated with long-term but not short-term mortality after cardiac valve replacement.

Background: The presence of multimorbidity is known to be related to adverse clinical outcomes. However, its association with mortality in patients undergoing cardiac valve replacement is not known.

Methods: Multimorbidity (as a continuous variable) was characterized in adults receiving cardiac valve replacement surgery between 2008 and 2012 within Kaiser Permanente Northern California based on information from health plan electronic health records. Our primary outcome was 3-year all-cause mortality after surgery. We used Cox proportional hazards regression to evaluate the independent association of each additional comorbidity with mortality.

Results: Among 3686 eligible patients, mean age was 67.9±13.5years and median comorbidity burden was 3 (IQR: 2). The presence of most individual comorbidities except hypertension and hyperlipidemia did not occur in isolation. The unadjusted annual incidence (per 100 person-years) of death increased with higher comorbidity burden: ≤1: 4.61 (95% CI: 3.29-6.45), 2-3: 13.7 (95% CI: 11.9-15.8), 4-5: 23.6 (95% CI: 20.6-26.9), and ≥6: 43.4(95% CI: 34.6-54.4). Advancing age, diabetes mellitus, cerebrovascular accident, heart failure, lung disease, urgent status and use of aldosterone-receptor antagonists were independently associated with an increased risk of mortality. In multivariable analyses, each additional comorbidity was significantly associated with an increased risk of long-term (adjusted hazard ratio (HR) 1.30, 95% CI: 1.22-1.39) but not short-term mortality (HR 0.92, 95% CI: 0.80-1.07).

Conclusions: Our study demonstrated that multimorbidity in patients undergoing cardiac valve replacement is significantly associated with long-term but not short-term mortality.