1. The risk of mortality is 4 times higher in women with previous myocardial infarction and 2 times higher in those with history of ischemic stroke.
2. The risk of total fatal and nonfatal cardiovascular events was 13 times higher in women with previous ischemic stroke.
Evidence Rating Level: 2 (Good)
Study Rundown: Surviving an ischemic stroke (IS) or myocardial infarction (MI) may put one at increased risk of mortality or morbidity. This is a particularly important for individuals who have suffered an IS or MI at a young age. However, information on the long-term mortality and morbidity after such events is sparse, especially for women. This long-term follow-up study analyzes the cohort from the Risk of Arterial Thrombosis in Relation to Oral Contraceptives (RATIO) study to determine the long-term mortality and morbidity in young women surviving IS or MI.
Women who had a previous MI had a 3.7 times higher rate of mortality as compared to controls. Those with previous IS had 1.8 times higher rate of mortality. The elevated risk persisted overtime and was owed to higher rates of acute vascular events. However, total cardiovascular events (i.e., fatal and nonfatal) were 13 times higher in women with previous IS than controls. Women with previous MI were more likely to incur subsequent cardiac events, whereas women with previous IS were more likely to incur subsequent cerebrovascular events. Strengths of this study included long follow-up, which is suited to the outcome of mortality due to cardiac events, as well as studying women, an often-underrepresented population. Limitations included survival bias, which may undermine the absolute risks immediately after the initial cardiovascular risk, as well as inability to control for changing risk factors, and treatment technologies, which may impact the causal link between exposure and outcome.
In-Depth [retrospective cohort]: This retrospective study created a cohort population based on the case-control data of the RATIO study from January 1995 to December 1998. Women who had no history of arterial thrombosis (i.e., MI or IS) were recruited as controls, and these two groups of women were followed until December 2012 for the study outcomes of mortality and first occurrence of any acute major cardiovascular or cerebrovascular event during follow-up. Statistical analysis included calculation of incidence rates and hazard ratios from multivariable Cox proportional regression models. Hazard ratios were adjusted for age, lifestyle (i.e., smoking, alcohol consumption, and BMI), comorbid disease (i.e., diabetes, hypertension and hypercholesterolemia) and family history of cardiovascular disease.
A total of 226 women with MI and 160 with IS with 782 controls were followed for a median of 18.7 years. In women with previous MI, mortality adjusted hazard ratios were 3.7 (95%CI 2.5-5.4) as compared to controls. Adjusted hazard ratios of mortality in women with history of IS were 1.8 (95%CI 1.0-3.5) as compared to controls. The main contributing factor to mortality was death from acute vascular events: mortality rate was 3.5 per 1000 person-years (95%CI 1.9-5.9) in women with MI, 2.1 per 1000 person-years (95%CI 0.8-4.5) in patients with stroke and 0.3 per 1000 person-years (95%CI 0.1-0.7) in controls. Women with history of stroke had the highest incidence of any cardiovascular event (fatal or non-fatal): 14.1 per 1000 person-years (95%CI 9.9-19.4), which was 13 times higher than matched controls. Women who had previous MI were more likely to have another MI, whereas women with previous IS were more likely to have another IS.
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