| Summary: | Cardiovascular diseases (CVD) are the number one cause of death worldwide. About one fifth of those who survived a myocardial infarction will suffer a recurrent cardiovascular event (CVE). Given the low participation in recommended cardiac rehabilitation, there is interest in early risk stratification after a primary CVE. This dissertation evaluates leisure time physical activity (LTPA), N-Terminal pro-Brain Natriuretic Peptide (NT-proBNP) and cystatin C as predictors of a secondary CVE in a German cohort of cardiac rehabilitation patients with stable coronary heart disease followed from 1999 to 2008.
Study 1 evaluated self-reported LTPA at one-year follow-up. Those reporting seldom/never practice of LTPA showed a higher risk (Hazard Ratio (HR) 1.30 [95% Confidence Interval (CI) 0.62, 2.69]), while those reporting LTPA at least 5-6 times/week had a reduced risk (HR 0.88 [95% CI 0.54, 1.43]) for a subsequent CVE, when compared to the reference group (1-4 times/month). Study 2 examined LTPA trajectories during the age period 20-49 years. Compared to those with a gradual decline of LTPA, the highest risk was observed among those with a steeper decrease of LTPA (HR 1.59 [95% CI 0.97, 2.62]). A continuous increase of LTPA was associated with a risk reduction (HR 0.71 [95% CI 0.41, 1.22]) with respect to a recurrent CVE.
Studies 3 and 4 evaluated the prognostic value of two novel biomarkers, when added to a model containing well-established CVD risk factors. In Study 3, NT-proBNP levels at one-year follow-up and a 10% increase in the slope of a NT-proBNP three-year trajectory were associated with a subsequent CVE ,with HRs of 1.63 [95% CI 1.17, 2.27] and 1.24 [95% CI 1.12, 1.37], respectively. One-year, but not baseline, levels of NT-proBNP showed an improvement in risk reclassification. Study 4 examined cystatin C versus creatinine. Although both were associated with a recurrent CVE, only the addition of cystatin C improved model performance, discrimination and reclassification.
In conclusion, in patients with stable coronary heart disease, LTPA, NT-proBNP, and cystatin C might help to identify individuals at high risk for a recurrent CVE. Further research is needed to evaluate treatment modalities for secondary prevention in this group.
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