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Antithrombotic treatment and the incidence of angina pectoris
Christine Knottenbelt1, Patrick J Brennan, Tom W Meade
1Medical Research Council's General Practice Framework, London, England. tom.meade@lshtm.ac.uk
Insights
Warfarin significantly reduced coronary heart disease (CHD) incidence in primary prevention. Aspirin, however, increased angina pectoris incidence, suggesting warfarin
Area of Science:
- Cardiology
- Preventive Medicine
- Pharmacology
Background:
- Warfarin and aspirin were previously shown to reduce coronary heart disease (CHD) incidence in primary prevention.
- The study investigated the effects of warfarin and aspirin on angina pectoris and total CHD.
- Warfarin's potential
Purpose of the Study:
- To assess the effects of warfarin and aspirin on the development of angina pectoris and total coronary heart disease (CHD) in primary prevention.
- To evaluate the potential
Main Methods:
- A factorial trial involving 5499 men aged 45-69 at increased risk of CHD.
- Four treatment groups: active warfarin/active aspirin, active warfarin/placebo aspirin, placebo warfarin/active aspirin, and double placebo.
- Identification of men developing angina pectoris, myocardial infarction, or coronary death.
Main Results:
- Warfarin showed a non-significant 16% reduction in stable angina incidence (P =.26), while aspirin increased it by 39% (P =.05).
- Warfarin use resulted in 37% less stable angina incidence compared to aspirin (P =.05).
- Warfarin significantly reduced total CHD by 18% (P =.01), whereas aspirin showed an 8% reduction (P =.36).
Conclusions:
- Findings suggest warfarin may have a durable effect on chronic pathologic conditions underlying angina.
- Further research is necessary to confirm these findings regarding warfarin's role in primary CHD prevention.
- The study highlights the potential implications of antithrombotic agents in primary prevention strategies.
Background:
In primary prevention, anticoagulation with warfarin sodium to an international normalized ratio of 1.5 and 75 mg of aspirin per day each reduced the incidence of coronary heart disease (CHD). Effects on the development of angina pectoris and total CHD (resulting from angina, myocardial infarction, and coronary death) have been assessed, particularly in light of recent evidence that warfarin may have a "durable effect" on CHD through effects on the pathologic condition of the vessel walls involved.
Methods:
The Thrombosis Prevention Trial was carried out in 5499 men aged 45 through 69 years who were at increased risk of CHD. The trial was factorial, with 1 group taking active warfarin and active aspirin, 1 taking active warfarin and placebo aspirin, 1 taking placebo warfarin and active aspirin, and 1 taking double placebo treatment. In addition to those with myocardial infarction and coronary death, men developing angina pectoris after entry to the trial were identified.
Results:
Warfarin appeared to reduce the incidence of stable angina by 16% (95% confidence interval [CI], -14 to 38), although not significantly (P =.26), while aspirin increased the incidence by 39% (95% CI, 0 to 91) (P =.05). The incidence of stable angina was 37% (95% CI, -1 to 60) less in those taking warfarin than in those taking aspirin (P =.05). Warfarin reduced total CHD by 18% (95% CI, 4 to 30) (P =.01), while the reduction due to aspirin was 8% (95% CI, -10 to 22) (P =.36).
Conclusions:
The results are compatible with the concept of a durable effect of warfarin on the chronic pathologic conditions underlying angina, although this has not been established with certainty. Further research is needed to confirm or refute our findings, because they carry potentially important implications for the primary prevention of CHD with the use of antithrombotic agents.