Effects of caffeine on fractional flow reserve values measured using intravenous adenosine triphosphate.

We investigated the effects of caffeine intake on fractional flow reserve (FFR) values measured using intravenous adenosine triphosphate (ATP) before cardiac catheterization. Caffeine is a competitive antagonist for adenosine receptors; however, it is unclear whether this antagonism affects FFR values. Patients were evenly randomized into 2 groups preceding the FFR study. In the caffeine group (n = 15), participants were given coffee containing 222 mg of caffeine 2 h before the catheterization. In the non-caffeine group (n = 15), participants were instructed not to take any caffeine-containing drinks or foods for at least 12 h before the catheterization. FFR was performed in patients with more than intermediate coronary stenosis using the intravenous infusion of ATP at 140 µg/kg/min (normal dose) and 170 µg/kg/min (high dose), and the intracoronary infusion of papaverine. FFR was followed for 30 s after maximal hyperemia. In the non-caffeine group, the FFR values measured with ATP infusion were not significantly different from those measured with papaverine infusion. However, in the caffeine group, the FFR values were significantly higher after ATP infusion than after papaverine infusion (P = 0.002 and P = 0.007, at normal and high dose ATP vs. papaverine, respectively). FFR values with ATP infusion were significantly increased 30 s after maximal hyperemia (P = 0.001 and P < 0.001 for normal and high dose ATP, respectively). The stability of the FFR values using papaverine showed no significant difference between the 2 groups. Caffeine intake before the FFR study affected FFR values and their stability. These effects could not be reversed by an increased ATP dose.

Analysis of suboptimal stent deployment using intravascular ultrasound and coronary pressure pullback measurement.

BACKGROUND: There are some cases in whom a sufficient improvement in fractional flow reserve (FFR) could not be achieved even if anatomical results indicated satisfactory stent deployment. We investigated the relation of abnormal findings between intravascular ultrasound (IVUS) and coronary pressure pullback measurement (CP-PB). METHODS: IVUS and CP-PB were investigated after stent deployment in 60 vessels in 53 patients. CP-PB criterion for adequate stent deployment was defined as a ratio of coronary pressure at the stent distal edge to the proximal edge (Psd/Psp) that is greater than 0.95. RESULTS: Residual pressure gradient across the stent which was indicated by Psd/Psp≤0.95 was present in 11 (18%), and four of them were caused by insufficient stent expansion (incomplete apposition and asymmetric dilation), and five of them were caused by issues with stent edge (edge dissection and incomplete coverage of the plaques). Insufficient FFR recovery which was recorded at distal part of target vessel was present in 10 (17%), and the main causes corresponded to inadequate stent deployment in half of the lesions, and presence of residual lesion at a non-stent segment in the other half. There were six lesions in whom Psd/Psp was ≤0.95 but FFR was ≥0.80. Disagreement between IVUS and CP-PB findings was seen in 12 (20%). CONCLUSIONS: Residual pressure gradient across the stent can reflect not only an insufficient stent expansion but also issues with stent edges. The decision of optimum stent deployment as assessed by IVUS and CP-PB was mismatched in 20% of cases, therefore careful attention should be paid to decoding the CP-PB findings.

Characterization of real-world patients with low fractional flow reserve immediately after drug-eluting stents implantation.

Fractional flow reserve (FFR)-guided percutaneous coronary intervention (PCI) for coronary artery disease has been validated. The present study aimed to identify the variables that influence FFR immediately after drug-eluting stents (DESs) implantation. We retrospectively analyzed 167 patients, who had been implanted with DESs at 6 Japanese institutions and had obtained the FFR values before and immediately after PCI. Intravascular ultrasound (IVUS) was used to build a PCI strategy and to decide the completion of the PCI procedure in all case. Patients were categorized into the following 2 groups according to FFR after PCI: the low FFR (≤0.80) group and the high FFR (>0.80) group. Despite successful PCI evaluated by coronary angiography and IVUS, 18.6 % of real-world patients were in the low FFR group. The proportion of the left anterior descending artery (LAD) was significantly greater in the low FFR group than in the high FFR group (87.1 vs 56.6 %; P < 0.01). Multivariate logistic regression analysis revealed that the LAD-to-non-LAD odds ratio for a low FFR (≤0.80) was 7.34 (95 % CI 1.63-32.95; P < 0.01) after adjustment for FFR value before PCI, suggesting that it is difficult to improve the hemodynamics of the LAD lesions even after successful PCI. The LAD was the strongest contributor to the inadequate recovery of FFR immediately after PCI, thus eliciting heed when treating the LAD lesions.

Papaverine-induced polymorphic ventricular tachycardia during coronary flow reserve study of patients with moderate coronary artery disease.

BACKGROUND: Papaverine is useful for evaluating the functional status of a coronary artery, but it may provoke malignant ventricular arrhythmia (VA). The aim of this study was to investigate the incidence, and clinical and ECG characteristics of patients with papaverine-induced VAs. METHODS AND RESULTS: The 182 consecutive patients underwent fractional flow reserve (FFR) measurement of 277 lesions. FFR was determined after intracoronary papaverine administration by standard procedures. The clinical and ECG characteristics were compared between patients with and without ventricular tachycardia (VT: ≥3 successive premature ventricular beats (PVBs), or ventricular fibrillation (VF)). After papaverine administration, the QTc interval, QTUc interval, and T-peak to U-end interval were prolonged significantly. Single PVBs on the T-wave or U-wave type developed in 29 patients (15.9%). Polymorphic VT (torsade de pointes) occurred in 5 patients (2.8%), and of those, VF developed in 3 patients (1.7%). No clinical and baseline ECG parameters were predictors for VT or VF except for sex and administration of papaverine into the left coronary artery. Excessive prolongation of QT (or QTU), T-peak to U-end intervals and giant T-U waves were found immediately prior to the ventricular tachyarrhythmias (VTAs), which were unpredictable from the baseline data. CONCLUSIONS: Intracoronary administration of papaverine induced fatal VTAs, although the incidence is rare. Excessive prolongation of the QT (and QTU) interval appeared prior to VTAs; however, they were unpredictable.

Seven-year clinical outcomes of patients with moderate coronary artery stenosis after deferral of revascularization based on gray-zone fractional flow reserve.

The range (0.75-0.80) of fractional flow reserve (FFR) is known as the gray zone. Although the FFR of 0.80 was recently adopted as the cutoff value for coronary revascularization, the long-term clinical outcomes of patients with angiographically moderate coronary artery stenosis (FFR: 0.75-0.80) remain unknown. The objective of the present study was to investigate the clinical outcomes of patients with angiographically moderate coronary artery stenosis, whose FFR was 0.75-0.80. One hundred and twenty consecutive patients, for whom coronary revascularization was deferred based on FFR, were categorized to groups I and II, in which 55 and 65 patients had FFRs of 0.75-0.80 and 0.81-0.85, respectively. Adverse cardiac events included all-cause death, cardiac death, myocardial infarction, coronary revascularization for the FFR-measured and -unmeasured arteries, congestive heart failure, and admission for chest symptoms. Patients were followed up for 7 years after coronary angiography. Event-free survival rates of all adverse cardiac events were 73 % in group I and 63 % in group II (P = 0.35) and those of adverse cardiac events related to the FFR-measured artery were 94 and 85 % (P = 0.08). Throughout the follow-up period, the medication rate of statins was significantly lower in group II than in group I (P = 0.008). Seven-year clinical outcomes of patients with the gray-zone FFR were good. Furthermore, FFR-measured artery-related events in patients with the gray-zone FFR tended to occur less frequently than in patients with better FFR of 0.81-0.85. Optimal medical therapy is required for them, regardless of coronary stenosis severity and FFR.