Hideki Kitahara

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.

Effect of pioglitazone on endothelial dysfunction after sirolimus-eluting stent implantation.

Previous studies have demonstrated endothelial dysfunction after sirolimus-eluting stent (SES) implantation. The present study evaluated the effect of pioglitazone on endothelial dysfunction after SES implantation in nondiabetic patients. A total of 50 nondiabetic patients who had undergone SES implantation were randomly assigned to the pioglitazone group (n = 25) or the control group (n = 25). Endothelial function was estimated by measuring the coronary vasoreactivity in the reference segment within 15 mm proximal and distal to the SES in response to intracoronary acetylcholine infusion (10(-8) and 10(-7) mol/L) at 9 months of follow-up. Endothelium-independent vasomotion was assessed after an intracoronary bolus of nitroglycerin. Changes in the coronary diameter in response to 10(-8) and 10(-7) mol/L acetylcholine in the segment proximal to the SES were not significantly different between the pioglitazone and control groups. In contrast, in the segment distal to the SES, vasoconstrictions to 10(-8) (-3.0 ± 2.8% vs -7.1 ± 4.5%, p <0.01) and 10(-7) mol/L acetylcholine (-6.2 ± 8.0% vs -13.1 ± 8.9%, p <0.01) were attenuated in the pioglitazone group compared to the control group. Endothelium-independent vasodilation to nitrate did not differ between the 2 groups. Multivariate analysis showed that pioglitazone was an independent predictor improving endothelial dysfunction after SES implantation. In conclusion, pioglitazone might improve endothelial dysfunction after SES implantation in nondiabetic patients.

Prevalence and Clinical Features of Focal Takotsubo Cardiomyopathy

BACKGROUNDnBecause it is difficult to distinguish between focal takotsubo cardiomyopathy and aborted myocardial infarction, there is little information about the prevalence and clinical features of focal takotsubo cardiomyopathy.nnnMETHODSANDRESULTSnOur cardiac catheterization databases were queried to identify patients with focal takotsubo cardiomyopathy and other types of takotsubo cardiomyopathy. We defined focal takotsubo cardiomyopathy as hypo-, a- or dyskinesis in both anterolateral and septal segments without obstructive coronary artery disease explaining the wall motion abnormality. A total of 10 patients were diagnosed with focal takotsubo cardiomyopathy. The control group comprised patients with takotsubo cardiomyopathy with apical, mid-ventricular, or basal ballooning. Clinical features and in-hospital outcomes were compared between patients with focal takotsubo cardiomyopathy and those with other types of takotsubo cardiomyopathy. Among the 144 patients with takotsubo cardiomyopathy, the apical, mid-ventricular, basal, and focal types occurred in 85 (59.0%), 49 (34.0%), 0 (0%), and 10 patients (6.9%), respectively. The left ventricular ejection fraction was significantly higher in the focal group compared with the apical and mid-ventricular group (56±13 vs. 45±13 vs. 46±12%, P=0.03). In-hospital outcome was not significantly different among the 3 groups.nnnCONCLUSIONSnFocal takotsubo cardiomyopathy is not rare. Biplane left ventriculography is useful for its diagnosis. (Circ J 2016; 80: 1824-1829).

Coronary artery endothelial dysfunction associated with sleep apnea.

There is little information about coronary artery endothelial dysfunction in patients with sleep apnea. We evaluated relation between severity of sleep apnea and coronary artery endothelial dysfunction. In all, 26 patients without significant coronary stenoses were enrolled. Endothelial function was estimated by measuring coronary vasoreactivity in response to acetylcholine infusion (10-7 mol/L) into coronary arteries. Vasoconstriction rate was defined as ([lumen diameter after isosorbide dinitrate injection - lumen diameter after acetylcholine injection]/lumen diameter after isosorbide dinitrate injection × 100). Vasoconstriction rate was calculated at each major coronary artery and the highest value was used for that patient. Overnight sleep study was performed and the apnea-hypopnea index (AHI) was calculated as the mean number of apneas and hypopneas per hour of sleep. There was significant correlation between AHI and vasoconstriction rate (P = .04). There is significant correlation between severity of sleep apnea and endothelial function of coronary arteries.

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

BACKGROUNDnStem 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.nnnMETHODSnOne 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.nnnRESULTSnFollow-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.nnnCONCLUSIONnGranulocyte 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.

Efficacy of combined administration of intracoronary papaverine plus intravenous adenosine 5′-triphosphate in assessment of fractional flow reserve

BACKGROUNDnInducing maximal coronary hyperemia is important to measure fractional flow reserve (FFR) accurately. Intravenous adenosine and adenosine 5-triphosphate (ATP) have been used to achieve maximal hyperemia. However, they may not induce maximal hyperemia in all patients. The present study evaluated the combined effect of intracoronary papaverine and intravenous ATP on FFR measurements.nnnMETHODSnFFR measurements with administration of intracoronary papaverine (12mg in the left coronary artery and 8mg in the right coronary artery), intravenous ATP (140μg/kg/min), and combined administration of intracoronary papaverine and intravenous ATP were performed in 51 patients with 57 intermediate lesions.nnnRESULTSnThe mean FFR after intravenous ATP was higher compared to intracoronary papaverine and intravenous ATP plus intracoronary papaverine (0.76±0.13 vs. 0.75±0.13 vs. 0.75±0.13, p=0.01). FFR-positive lesions (FFR ≤0.80) were observed more frequently with intravenous ATP plus intracoronary papaverine compared to intravenous ATP (64.9% vs. 47.4%, p=0.02). Of 32 and 25 FFR-negative lesions with intravenous ATP and intracoronary papaverine, 11 (34%) and 7 (28%) had positive FFR after administration of intravenous ATP plus intracoronary papaverine. No ventricular tachycardia or ventricular fibrillation was observed after administration of intracoronary papaverine.nnnCONCLUSIONSnMaximal hyperemia may not be induced with intravenous ATP in all lesions. When sufficient hyperemia is doubtful during intravenous infusion of ATP, additional intracoronary administration of papaverine may be a possible option.

Efficacy and safety of low-dose clopidogrel in Japanese patients after drug-eluting stent implantation: a randomized pilot trial

In Japan, a lower maintenance dose of ticlopidine is used than in the United States and Europe. Therefore a lower maintenance dose of clopidogrel may also be considered appropriate in Japanese patients. The present randomized pilot study evaluated the efficacy and safety of 50 mg clopidogrel in Japanese patients who underwent drug-eluting stent (DES) implantation. A total of 200 patients with 277 lesions who underwent intravascular ultrasound-guided DES implantation were enrolled. The subjects were allocated to the 50- or 75-mg clopidogrel group. All patients received 100 mg aspirin daily before the procedure, and this continued indefinitely. The duration of clinical follow-up was 21.8 ± 5.7 months in the 75-mg group and 21.9 ± 6.1 months in the 50-mg group (P = 0.96). During follow-up, no cardiac death, myocardial infarction, or stent thrombosis was observed in either group. Side effects of clopidogrel were observed in 4 patients (4.0 %) in the 75-mg group and in 4 patients (4.0 %) in the 50-mg group. Following this randomized pilot study, it may be justified to perform a large-scale randomized study comparing 50- and 75-mg dosing of clopidogrel in Japanese patients undergoing coronary stent implantation.

Impact of myocardial bridging on in-hospital outcome in patients with takotsubo syndrome

BACKGROUNDnPrevalence of myocardial bridging of the left anterior descending coronary artery (LAD) in patients with takotsubo syndrome (TTS) has been demonstrated. However, the impact of myocardial bridging on in-hospital outcome has not been fully evaluated.nnnMETHODSnA total of 144 consecutive patients with TTS were enrolled. Coronary angiography and left ventriculography were performed in all patients and absence of obstructive coronary disease explaining the left ventricular contraction abnormality was confirmed. Myocardial bridging was diagnosed when a dynamic compression in systole, so-called milking effect, was observed in the LAD. We evaluated differences in the clinical characteristics and in-hospital outcome between patients with and without myocardial bridging. Furthermore, multiple logistic regression analysis was performed to predict in-hospital death.nnnRESULTSnMyocardial bridging was observed in 33 patients (23%). In-hospital death was more frequent in patients with myocardial bridging (21% vs. 6%, p=0.02), which was due mainly to a higher non-cardiac death in those patients (15% vs. 5%, p=0.049). Multiple logistic regression analysis demonstrated myocardial bridging (odds ratio=12.0, 95% CI=2.52-78.5, p<0.01) as one of the independent predictors of in-hospital death.nnnCONCLUSIONnMyocardial bridging is an independent predictor of in-hospital death in patients with TTS.