Cardiac troponin and increased mortality risk among individuals with restrictive spirometric pattern on lung function testing

Background: Individuals with a restrictive spirometric pattern have a high burden of cardiovascular and metabolic morbidity. Objective: To assess prevalence of elevated cardiac biomarkers among individuals with a restrictive spirometric pattern compared to those with a normal lung function and to evaluate the association between cardiac biomarkers and mortality. Methods: In 2002-04, individuals with airway obstruction were identified from population-based cohorts, together with age- and sex-matched non-obstructive referents. The analysis population consisted of the non-obstructive referents stratified according to whether they had a restrictive spirometric pattern or normal lung function in whom cardiac biomarkers were measured. Deaths were recorded until 31 December 2010. Results: Participants with a restrictive spirometric pattern were older and more likely to be obese with a higher burden of cardiovascular risk factors than those with normal function. Elevated cardiac troponin but not natriuretic peptide levels were more common in those with a restrictive spirometric pattern independent of age, sex, BMI, or risk factors (adjusted OR 1.8, 95% CI 1.29-2.74). At 5 years, death occurred more frequently in participants with restrictive spirometric pattern compared to those with normal function (15.7% [31/197] versus 7.6% [57/751]), with highest mortality rate in those with restriction and elevated cardiac troponin (28.7% [27/94]). Cardiac troponin was independently associated with death among those with a restrictive spirometric pattern (HR 4.91, 95% CI 1.58-15.26) but not in those with normal lung function. Conclusion: Cardiac troponin was elevated more often in people with a restrictive spirometric pattern in whom it was a strong independent predictor of death.