Kenichi Fukushima

Effect of balloon inflation time on expansion of sirolimus-eluting stent

There is little information about the relationship between balloon inflation time and sirolimus-eluting stent (SES) expansion. In this randomized intravascular ultrasound (IVUS) study, 92 de novo lesions in native coronary arteries that underwent SES implantation were enrolled. Sirolimus-eluting stent was implanted using an inflation pressure of 14 atm. Stent balloon was gradually inflated until 14 atm in 10 s. In the short inflation group, it was deflated immediately after an image of the balloon inflated at 14 atm was taken. Stent balloon inflation lasted 60 s in the long inflation group. Intravascular ultrasound was then performed. The long balloon inflation resulted in a larger stent cross-sectional area (4.9 ± 1.6 mm2 vs 4.3 ± 1.4 mm2, P < 0.05) and expansion (71% ± 13% vs 60% ± 13%, P < 0.001) compared to the short balloon inflation, although stent expansion was relatively low in both groups. The relatively longer balloon inflation time using an inflation pressure of 14 atm results in better SES expansion. However, in the majority of lesions, adequate stent expansion is not achieved even using long balloon inflation, if it is inflated at 14 atm.

Ubiquitous atherosclerosis in coronary arteries without angiographically significant stenosis

Previous intravascular ultrasound (IVUS) studies have shown coronary artery atherosclerosis even in angiographically normal reference segment. However, IVUS has not been performed in all of the three major coronary arteries. A total of 50 patients with single-vessel disease underwent IVUS evaluation in the proximal two-thirds of the three major coronary arteries. Lumen and external elastic membrane cross-sectional areas were measured at 1-mm intervals. To compensate the difference in pullback length among coronary arteries, normalized total plaque and media volume (TPV) was calculated as TPV/number of slices in pullback × median number of slices in study population. Percent plaque and media volume (PPV) was calculated as TPV/Σ external elastic membrane cross-sectional area × 100. A cross section was defined as atherosclerotic if maximum intimal thickness exceeded 0.5 mm at any point in the vessel circumference. There was no significant difference in normalized TPV, PPV, and the incidence of abnormal intimal thickness between coronary arteries with and without significant stenosis. Frequency distribution of plaque burden was similar. Atherosclerosis is ubiquitous even in coronary arteries without angiographically significant stenosis. The extent of atherosclerosis is similar between coronary arteries with and without significant stenosis.

Effects of stem cell mobilization by granulocyte colony-stimulating factor on endothelial function after sirolimus-eluting stent implantation: A double-blind, randomized, placebo-controlled clinical trial

BACKGROUND Stem cell mobilization by granulocyte colony-stimulating factor (G-CSF) has been shown to enhance endothelial healing after spontaneous or iatrogenic arterial disruption. Granulocyte colony-stimulating factor treatment might attenuate endothelial dysfunction after sirolimus-eluting stent (SES) implantation that may be associated with adverse cardiac events during follow-up. This prospective, double-blind, randomized, placebo-controlled study investigated whether G-CSF improved endothelial dysfunction after SES implantation. METHODS One hundred patients who underwent SES implantation were randomly assigned to the G-CSF (n = 50) or the placebo group (n = 50). They received daily subcutaneous injection of 300 μg G-CSF or saline for 5 days. Endothelial function was estimated by measuring the coronary vasoreactivity in the segments 15 mm proximal and distal to SES in response to intracoronary infusion of acetylcholine (10(-8) and 10(-7) mol/L) at 9-month follow-up. RESULTS Follow-up angiography was performed in 41 G-CSF patients (82%) and 46 placebo patients (92%) (P = .14). Changes in coronary diameter in response to acetylcholine infusion in the proximal segment were not significantly different between the 2 groups. However, vasoconstriction in the distal segment in response to 10(-8) mol/L (-3.9% ± 6.4% vs -7.0% ± 8.1%, P < .05) and 10(-7) mol/L (-8.8% ± 11.0% vs -15.2% ± 7.6%, P < .01) acetylcholine infusion was attenuated in the G-CSF group. Endothelium-independent vasodilatation after nitrate infusion did not differ between the 2 groups. CONCLUSION Granulocyte colony-stimulating factor attenuates endothelial dysfunction after SES implantation.

Antiplatelet effect of 50-mg maintenance dose of clopidogrel compared to 200 mg ticlopidine: a preliminary study

In the United States and Europe, patients with coronary stents are maintained on 75 mg clopidogrel. Because the maintenance dose of ticlopidine in patients with coronary stents is 100 mg twice daily in Japan and 250 mg twice daily in the United States and Europe, in Japanese patients a lower dose of clopidogrel may achieve an antiplatelet effect comparable to 200 mg ticlopidine. Platelet aggregation was evaluated in 104 consecutive patients on 50 mg clopidogrel plus aspirin (n = 54) and 200 mg ticlopidine plus aspirin (n = 50). Platelets were stimulated with adenosine diphosphate (5 and 20 μmol/l) and aggregation was assessed by optical aggregometry. There was no significant difference in platelet aggregation induced with 5 (37% ± 11% vs 38% ± 15%, not significant) and 20 μmol/l adenosine diphosphate (48% ± 13% vs 51% ± 12%, not significant) between 50 mg clopidogrel and 200 mg ticlopidine. In Japanese patients, there is the possibility that a maintenance dose of 50 mg clopidogrel on platelet inhibition is comparable to 200 mg ticlopidine.

Effect of 450-mg loading dose of clopidogrel on platelet function in Japanese patients undergoing coronary stent placement

Usefulness of higher (>300 mg) loading doses of clopidogrel has been demonstrated in studies from the United States and Europe. The present study evaluated platelet aggregation after the administration of a 450-mg loading dose of clopidogrel in Japanese patients undergoing coronary stenting. Platelet aggregation was serially measured at baseline, and 2, 4, 6, and 8 h after 450-mg clopidogrel loading in 25 patients undergoing coronary stenting. Platelets were stimulated with 5 and 20 μmol/l adenosine diphosphate (ADP) and aggregation was assessed by optical aggregometry. Platelet aggregation (5 μmol/l ADP 42.8% ± 13.5% and 20 μmol/l ADP 51.2% ± 11.6%) was significantly suppressed ≤4 h after 450-mg clopidogrel loading. There were no adverse events except one minor nasal bleed. The present study shows that platelet inhibition is achieved ≤4 h after the administration of a 450-mg clopidogrel loading dose in Japanese patients.