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Elevation of C-reactive protein in "active" coronary artery disease
B C Berk1, W S Weintraub, R W Alexander
1Department of Medicine, Emory University School of Medicine, Atlanta, Georgia 30322.
Insights
Unstable angina is linked to elevated C-reactive protein (CRP), an inflammation marker. This suggests inflammation plays a role in unstable angina, potentially increasing risks of vasospasm and thrombosis in coronary artery disease patients.
Area of Science:
- Cardiology
- Immunology
- Biochemistry
Background:
- Unstable angina often arises from atherosclerotic coronary artery disease (CAD).
- Mechanisms driving the shift from stable to unstable plaque are poorly understood.
- Recent observations indicate increased inflammation in CAD, including neutrophil activation.
Purpose of the Study:
- To investigate the presence of inflammation in active atherosclerotic lesions.
- To measure C-reactive protein (CRP) levels in patients with unstable angina, stable CAD, and non-ischemic illnesses.
Main Methods:
- CRP levels were measured in 37 unstable angina patients, 30 non-ischemic CCU patients, and 32 stable CAD patients.
- CRP levels were compared across the three groups.
- CRP values were analyzed in relation to electrocardiographic changes.
Main Results:
- CRP levels were significantly elevated in 90% of unstable angina patients (average 2.2 mg/dl) compared to stable CAD (13%, 0.7 mg/dl) and non-ischemic CCU groups (20%, 0.9 mg/dl).
- Average CRP values were significantly different between unstable angina and the other two groups (p=0.001).
- A trend suggested higher CRP in unstable angina patients with ischemic changes.
Conclusions:
- Unstable angina is associated with increased levels of the acute phase reactant CRP.
- These findings support the role of inflammation in "active" angina.
- Inflammation may contribute to vasospasm and thrombosis susceptibility in unstable angina patients.
Abstract:
Unstable angina occurs most commonly in the setting of atherosclerotic coronary artery disease (CAD), but there is little information concerning the mechanisms responsible for the transition from clinically stable to unstable coronary atherosclerotic plaque. Recently, increased focal infiltration of inflammatory cells into the adventitia of coronary arteries of patients dying suddenly from CAD and activation of circulating neutrophils in patients with unstable angina have been observed. To characterize the presence of inflammation in "active" atherosclerotic lesions, the acute phase reactant C-reactive protein (CRP) was measured in 37 patients admitted to the coronary care unit with unstable angina, 30 patients admitted to the coronary care unit with nonischemic illnesses and 32 patients with stable CAD. CRP levels were significantly elevated (normal less than 0.6 mg/dl) in 90% of the unstable angina group compared to 20% of the coronary care unit group and 13% of the stable angina group. The average CRP values were significantly different (p = 0.001) for the unstable angina group (2.2 +/- 2.9 mg/dl) compared to the coronary care (0.9 +/- 0.7 mg/dl) and stable angina (0.7 +/- 0.2 mg/dl) groups. There was a trend for unstable angina patients with ischemic ST-T-wave abnormalities to have higher CRP values (2.6 +/- 3.4) than those without electrocardiographic changes (1.3 +/- 0.9, p = 0.1). The data demonstrate increased levels of an acute phase reactant in unstable angina. These findings suggest that an inflammatory component in "active" angina may contribute to the susceptibility of these patients to vasospasm and thrombosis.