Racial Differences in the Coronary Microcirculation

The safety and scientific validity of this study is the responsibility of the study sponsor and investigators. Listing a study does not mean it has been evaluated by the U.S. Federal Government. Read our disclaimer for details. Identifier: NCT00005373
Recruitment Status : Completed
First Posted : May 26, 2000
Last Update Posted : May 13, 2016
Information provided by:
National Heart, Lung, and Blood Institute (NHLBI)

Brief Summary:
To study mechanisms of excess coronary ischemia secondary to alterations in autoregulation and arteriolar vasoreactivity in Black Americans with hypertension, varying degree of left ventricular hypertrophy, and angiographically normal or mildly diseased coronary arteries.

Condition or disease
Cardiovascular Diseases Heart Diseases Coronary Disease Hypertension Myocardial Ischemia Hypertrophy, Left Ventricular

Detailed Description:


Although studies in 1992 with a sufficient number of minority patients were sparse, those available suggested that Black Americans had a higher case fatality from coronary heart disease, but lesser amounts of atherosclerotic coronary artery disease. A possible explanation for this apparent paradox was that myocardial ischemia might be more prevalent with less coronary artery atherosclerosis in Black Americans because of comorbid diseases or differences in coronary physiology. This could be secondary to excess hypertension and left ventricular hypertrophy in Black Americans but might also have been related to intrinsic or acquired differences in coronary artery autoregulation and vasoreactivity leading to depression in coronary blood flow and reserve.


The intracoronary Doppler flow velocity guidewire together with quantitative coronary angiography was used to study changes in coronary blood flow in blacks secondary to pharmacologic provocateurs known to induce arteriolar vasodilation. White Americans with similar demographic characteristics and equivalent amount of ventricular hypertrophy and coronary disease were similarly studied in a parallel fashion for comparison. A control group of normal white and Black Americans were studied to detect unexpected intrinsic differences. Both endothelium dependent and independent induction of coronary arteriolar vasodilation were studied. In 25 percent of patients with endothelium dependent defects in arteriolar vasodilation, retesting was performed after intracoronary infusion of L-arginine, the precursor of endothelium dependent relaxing factor. Finally, the possibility of a rightward shift in coronary artery autoregulation in chronic hypertension was investigated. This finding would necessitate that the lower limit of autoregulation occurred at higher diastolic pressures, resulting in a drop-off of coronary perfusion at normal physiologic pressures and ischemia.

The study completion date listed in this record was obtained from the "End Date" entered in the Protocol Registration and Results System (PRS) record.

Study Type : Observational
Study Start Date : September 1992
Actual Study Completion Date : August 1998

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Ages Eligible for Study:   up to 100 Years   (Child, Adult, Older Adult)
Sexes Eligible for Study:   Male
Accepts Healthy Volunteers:   No
No eligibility criteria

Publications: Identifier: NCT00005373     History of Changes
Other Study ID Numbers: 4267
R01HL050262 ( U.S. NIH Grant/Contract )
First Posted: May 26, 2000    Key Record Dates
Last Update Posted: May 13, 2016
Last Verified: July 2000

Additional relevant MeSH terms:
Cardiovascular Diseases
Heart Diseases
Coronary Disease
Coronary Artery Disease
Myocardial Ischemia
Hypertrophy, Left Ventricular
Pathologic Processes
Vascular Diseases
Arterial Occlusive Diseases
Pathological Conditions, Anatomical