Yukihiko Matsuno

Three minute, but not one minute, ischemia and nicorandil have a preconditioning effect in patients with coronary artery disease.

OBJECTIVES This study focused on 1) the determination of the optimal preconditioning (PC) duration, and 2) the protective effect of nicorandil (NC), a hybrid nitrate with a KATP channel opening effect, during a percutaneous transluminal coronary angioplasty (PTCA) model in humans. BACKGROUND The ischemic PC effect is induced in 180 s ischemia, but not in 120 s ischemia in rabbit hearts. However, the duration of ischemia that induces PC effect and the role of the KATP channel in the PC effect in humans are still unclear. METHODS Forty-six patients with stable angina were randomly allocated to four groups: the duration of the first inflation as PC ischemia was 60 s in the PC60 group (n = 12), and 180 s in the PC180 group (n = 12). In the other groups, NC (80 microg/kg) was intravenously given for 1 min in the NC group (n = 12), and isosorbide dinitrate (ISDN) (40 microg/kg) was given in the ISDN group (n = 10). Five minutes after first inflation or drug administration, a second inflation was conducted for 120 s in each group. In the ECG, the lead with the largest shift in ST segment (deltaST max), and the sum of elevated ST levels in all leads (sigmaST) were determined. RESULTS In the PC60 group, no significant difference was observed in either deltaST max or sigmaST between the first and second inflation. However, the second inflation in the PC180 group showed significantly lower levels of deltaST max and sigmaST compared with those of the first inflation. In the NC group, both deltaST max and sigmaST measured at 30 s and 60 s after balloon inflation were significantly lower than those of the first inflation in the PC60 and PC180 control groups. In the ISDN group, no significant difference was observed in deltaST max or sigmaST. CONCLUSION In human PTCA models, a PC effect is observed in 180 s ischemia, but not in 60 s ischemia. A pharmacological PC effect is induced by NC, a KATP channel opener with a nitrate-like effect but not ISDN. This suggests that the opening of KATP channels plays an important role in the protecting effect of NC.

Assessment of area at risk and efficacy of treatment in patients with acute coronary syndrome using99mTc tetrofosmin imaging in humans

The determination of the myocardium at risk before intervention and the change in that region after intervention constitute a promising measurement tool for the assessment of acute therapy. A new99mTc labeled myocardial blood flow tracer,99mTc tetrofosmin, is expected to enable the evaluation of myocardium at risk because of the absence of redistribution. This preliminary study was performed in 9 patients with acute coronary syndrome (4 unstable angina and 5 acute myocardial infarction) to investigate whether recovery of perfusion by tetrofosmin imaging parallels mechanical improvement. Tetrofosmin imaging was performed acutely and 3–30 days later. Visual analysis of defect severity was assessed in both studies. Segments with improvement in perfusion were accompanied by significant wall motion recovery compared with normal and unimproved segments (Δ WMI: normal segments 0.40±0.67, improved segments 1.79±0.68, unimproved segments −0.15±0.16, p< 0.01 for improved segments compared with other groups), suggesting the efficacy of this tracer for the assessment of the acute therapy. These data suggest that99mTc tetrofosmin imaging is a useful method for the assessment of the myocardial area at risk and the efficacy of acute therapy in acute myocardial infarction and unstable angina.

Identification of asynergic but viable myocardium in patients with chronic coronary artery disease by gated blood pool scintigraphy during isosorbide dinitrate and low-dose dobutamine infusion: Comparison with thallium-201 scintigraphy with reinjection

To evaluate the ability of low-dose dobutamine and isosorbite dinitrate (ISDN) gated blood pool scintigraphy (GBPS) and thallium SPECT with reinjection to identify viability in asynergic myocardium, both procedures were performed in 38 consecutive patients with chronic coronary artery disease and left ventricular dysfunction. Twenty-two of the 38 patients with successful revascularization were analyzed. GBPS was performed at the baseline and during continuous infusion of low dose dobutamine (5 μg/kg/min) and ISDN (2 μg/kg/min). Cine mode GBPS wall motion was scored from normal (0) to dyskinesis (4) semiquantitatively. Forty-seven of 110 segments with severe asynergy at the baseline were analyzed. Viability determined by GBPS was defined as wall motion score improvement by more than 1 grade. Thallium viability was defined as the segment with redistribution or fill in with severe initial perfusion defect. GBPS was 76.7% sensitive and 70.6% specific for predicting post vascularization wall motion improvement (p < 0.005). Of 47 segments with severe asynergy, concordance of judgement was obtained in 40 segments (85.1 %), and reversibility was correctly diagnosed in 34 of 40 patients (85.0%), but thallium with reinjection correctly identified tissue viability in 6 of 7 segments with discordance between 2 studies.These data suggest that most cases of reversible asynergy (hibernating myocardium) respond to ISDN and dobutamine, suggesting the possibility of predicting improvement by revascularization, although some underestimation of tissue viability remained to be resolved. Thallium with reinjection is superior to low-dose dobutamine + ISDN GBPS for the assessment of myocardial viability.

Myocardial perfusion during transient slow-flow in the patient with old vein graft intervention: assessment by serial measurement of pressure-derived fractional flow reserve and thermodilution-derived coronary flow reserve.

A patient with distal slow‐flow after stenting in the old vein graft intervention was reported. This case is a first in whom guidewire‐based serial measurement of pressure‐derived fractional flow reserve (FFRmyo) and thermodilution‐based coronary flow reserve (CFRthermo) clearly demonstrated the serial change of microvascular circulation. During slow‐flow, CFRthermo remained in low value despite significant improvement of FFRmyo from 0.61 to 0.90. After thrombus aspiration and nicorandil injection, coronary flow reestablished immediately. CFRthermo improved significantly from 1.3 during slow‐flow to 3.6 after restoration of flow. Catheter Cardiovasc Interv 2003;60:392–398.