The prevalence of the CSFP among patients undergoing diagnostic angiography is 1 percent when the phenomenon is defined as TIMI-2 flow in the absence of obstructive epi-cardial coronary artery disease. The associated epicardial artery morphology and angiographic flow have been characterized in 65 patients with the CSFP . Smooth contoured vessels were found in 74 percent of patients, coronary ecta-sia in 14 percent, and minor epicardial coronary artery disease (less than a 50% lesion) in 12 percent of CSFP patients. Thus the CSFP is seldom due to a capacitance effect from large ectatic epicardial coronary arteries.
Examination of the opacification rate (heart beats to fill a vessel) for the major epicardial vessels reveals that the LAD takes the longest to opacify in patients with the CSFP, followed by the right coronary and circumflex arteries (3.6 ± 1.2, 3.0 ± 1.1, and 2.4 ± 1.0 beats, respectively). This would be expected on the basis of the respective vessel lengths; however, if the angiographic flows are assessed by the TFC with normalization for their respective lengths, the LAD still exhibits a more delayed angiographic flow compared with the other vessels in the CSFP. Alternatively, if the frequency of a vessel exhibiting TIMI-2 flow is examined, the LAD is involved in 86 percent of patients, the RCA in 63 percent, and the Cx in 37 percent. This reflects the heterogeneous distribution of flow in the CSFP, although two-thirds of patients have TIMI-2 flow in multiple vessels.
Angiographic technical artifacts such as poor catheter engagement may potentially mimic the CSFP; however, these are readily recognized and excluded by experienced angiographers. A reduced perfusion pressure or myocardial oxygen demand may also be associated with reduced coronary angiographic flow. However, hemodynamic measurements recorded during angiography show no difference in central arterial pressure, epicardial artery diameter, and rate pressure product between patients with the CSFP and controls. Hence, in most patients, this angiographic phenomenon cannot be attributed to secondary changes in coronary blood flow.
Although the severity of the CSFP varies with time, serial studies in affected patients demonstrate a persistence in the delayed opacification. In a study of 12 patients with the CSFP who underwent repeat elective angiography at median interval of 7 months from the index study (range: 1 week to 10 years), the vessel opacification rates were similar (Figure 1). However, when the repeat study was compared with controls who do not have CSFP, vessel opacification remained considerably delayed (Figure 1).
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