Cardiovascular outcomes in patients at high cardiovascular risk with previous myocardial infarction or stroke

Background: Guidelines recommend to start blood pressure (BP)-lowering drugs also according to cardiovascular risk including history of cardiovascular events. We hypothesized that in patients with a history of myocardial infarction (MI), stroke, both or none of those, the index events predict the next event and have different SBP risk associations to different cardiovascular outcomes.

Design and measurements: In this pooled posthoc, nonprespecified analysis, we assessed outcome data from high-risk patients aged 55 years or older with a history of cardiovascular events or proven cardiovascular disease, randomized to the Ongoing Telmisartan Alone and in Combination with Ramipril Global Endpoint Trial and to Telmisartan Randomized Assessment Study in ACE Intolerant Subjects with Cardiovascular Disease Trial investigating telmisartan, ramipril and their combination with a median follow-up of 56 months. Standardized office BP was measured every 6 months. Associations of mean achieved BP on treatment were investigated on MI, stroke and cardiovascular death. We identified patients with previous MI (N = 13 487), stroke (N = 4985), both (N = 1509) or none (N = 10 956) of these index events. Analyses were done by Cox regression, analysis of variance and Chi2-test. 30 937 patients with complete data were enrolled between 1 December 2001 and 31 July 2003, and followed until 31 July 2008. Data of both trials were pooled as the outcomes were similar.

Results: Patients with MI as index event had a higher risk to experience a second MI [hazard ratio 1.42 (confidence interval (CI) 1.20-1.69), P < 0.0001] compared with patients with no events but no increased risk for a stroke as a next event [hazard ratio 0.95 (CI 0.73-1.23), n.s.]. The risk was roughly doubled when they had both, MI and stroke before [hazard ratio 2.07 (CI 1.58-2.71), P < 0.0001]. Patients with a stroke history had a roughly three-fold higher likelihood to experience a second stroke [hazard ratio 2.89 (CI 2.37-3.53) P < 0.0001] but not MI [hazard ratio 1.07 (CI 0.88-1.32), n.s.]. Both types of index events increased roughly three-fold the risk of a second stroke compared with no previous events. The SBP-risk relationship was not meaningfully altered by the event history. After MI and stroke the risk for subsequent events and cardiovascular death was increased over the whole SBP spectrum. A J-shape relationship between BP and outcome was only observed for cardiovascular death.

Conclusion: Previous MI and previous stroke are associated with increased risk for the same event in the future, independent of achieved SBP. Thus, secondary prevention may also be chosen according to the event history of patients.

Clinical trial registration: http://clinicaltrials.gov. Unique identifier: NCT00153101.