Warfarin and Coronary Calcification Project

Completed

Brief Summary: The purpose of the study is to assess whether the use of warfarin, a commonly used anticoagulation drug, is associated with increased amounts of coronary artery calcification. Studies in animals and preliminary but small retrospective studies in humans have suggested a possible link to increased tissue calcification with use of this drug. The researchers will investigate this by assessing the amount of calcification seen in the coronary arteries using a specialized computed tomography (CT) scan (electron-beam CT) and assessing to see if the amount is influenced by the amount of time a patient has been taking warfarin. The researchers will exclude patients with known coronary artery disease, chronic kidney disease or hyperparathyroidism.

Recruitment & Eligibility

Inclusion Criteria

Age 18 years of age or older
Patients referred to begin or already treated with warfarin anticoagulation therapy.

Exclusion Criteria

Known prior myocardial infarction or coronary heart disease
History of advanced chronic kidney disease manifested by serum creatinine>2 or calculated glomerular filtration rate (GFR)<30
History of hyperparathyroidism
Current hypercalcemia
Current hyperphosphatemia
Uncertain duration of warfarin therapy
Lack of records documenting international normalized ratio (INR) during therapy

Primary Outcome Measures

Name	Time	Method
Coronary Calcification (Presence and Degree as Measured by Agatston Score) Attributed to Duration of Warfarin Use in Months After Controlling for Standard Cardiovascular Risk Factors to Include the Framingham Risk Score	EBCT scan is done at time of enrollment of patient into 1 of 3 groups based on warfarin use duration: <6 months; 6-24 months; >24 mos.	The Agatston score is calculated using a non-contrast computed tomography (CT) scan to measure for the presence and severity of coronary artery disease through identification of calcification in the coronary arteries. Scores can range from 0 to several thousands. The measure is without units. Score categories are as follows: 0 = no coronary disease; 1-100 = low amount of coronary artery disease; 101-400 = moderately elevated score / moderate coronary artery disease; 401-1000 = severely elevated score; \>1000 very severely elevated score. Higher Agatston scores corelate with more coronary artery disease and predict a higher risk of coronary heart disease events and mortality.

Secondary Outcome Measures

Name	Time	Method
International Normalized Ratio	EBCT scan is done at time of enrollment of patient into 1 of 3 groups based on warfarin use duration: <6 months; 6-24 months; >24 mos.	The International Normalized Ratio (INR) is a standardized lab value that measures the intensity of anticogulation using warfarin. It is used to monitor patients taking warfarin.