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Management of patients with unstable angina in a general cardiology unit
L Wilkinson1, C J Ellis, G D Gorden
1Department of Medicine, Auckland Hospital.
Insights
Unstable angina patients had low inpatient deaths but a 12% risk of myocardial infarction. Braunwald risk stratification identified high-risk patients likely to have cardiac events, though its clinical utility varied.
Area of Science:
- Cardiology
- Clinical Medicine
- Risk Stratification
Background:
- Unstable angina requires effective clinical management and risk assessment.
- The Braunwald criteria offer a method for stratifying patients based on cardiovascular event risk.
Purpose of the Study:
- To review the clinical management of unstable angina patients.
- To prospectively evaluate the Braunwald criteria for risk stratification against subsequent cardiovascular events.
Main Methods:
- A three-month prospective review of 104 unstable angina patients admitted to Auckland Hospital's coronary care unit.
- Classification of patients into high, intermediate, or low risk using Braunwald criteria.
Main Results:
- 12% of patients experienced myocardial infarction, predominantly in the high-risk group (p=0.038).
- Inpatient mortality was low (1 death).
- Revascularization (PCI or CABG) was performed in 20% of patients, with 12 of these in the high-risk group.
Conclusions:
- Unstable angina patients have low inpatient mortality but a significant risk of myocardial infarction.
- Braunwald high-risk stratification correlated with increased myocardial infarction risk.
- The clinical utility of Braunwald criteria in the New Zealand context for guiding management and revascularization was limited.
Aims:
To review the clinical management of patients with unstable angina and to relate prospectively initial risk stratification, according to the Braunwald criteria, to subsequent cardiovascular events.
Methods:
From February to April 1996 we performed a three month prospective review of all patients with a diagnosis of unstable angina admitted to the coronary care unit at Auckland Hospital.
Results:
One hundred and four patients (61% male), with a mean age of 64 years, were classified as high (58%), intermediate (41%) or low risk (1%) for an adverse cardiac event. Twelve (12%) patients had a documented myocardial infarction, of whom 11 were in the high-risk group (p = 0.038). During hospitalisation there was one death. Twelve (12%) patients underwent inpatient exercise testing, five of whom proceeded to a coronary angiogram prior to hospital discharge. Twenty-two (21%) unstable patients underwent inpatient angiography without prior exercise testing. Twenty-one (20%) patients required revascularisation on the same admission: percutaneous coronary angioplasty (n = 14) or coronary artery bypass grafting (n = 7). Twelve of these 21 patients were in the high-risk group (p = 0.999, NS).
Conclusion:
Patients admitted with unstable angina had low inpatient mortality but a 12% rate of subsequent myocardial infarction. Braunwald low-risk unstable angina patients were not admitted to the coronary care unit. Braunwald high-risk patients were more likely to develop a subsequent myocardial infarction. Stratification of patients into intermediate or high-risk groups did not relate to initial medical management or subsequent revascularisation. Thus, while this method of risk stratification may predict cardiovascular events, it may be of limited clinical use in the New Zealand environment.