Difference In Fractional Flow Reserve Research Articles

The value of fractional and coronary flow reserve in predicting myocardial recovery in patients with previous myocardial infarction

The aim of the study was to evaluate the relation between fractional flow reserve (FFR) and simultaneously evaluated coronary flow reserve by thermodilution (CFRthermo), with the improvement of left ventricular (LV) function in patients with previous myocardial infarction (MI) undergoing percutaneous coronary intervention (PCI). Study population consisted of 46 patients (mean age 53 +/- 7 years; 36 male) with previous MI and significant coronary stenosis undergoing PCI of infarct-related coronary artery. In all patients, we evaluated FFR and CFRthermo by single pressure/thermo wire during maximal hyperaemia before and immediately after PCI. We performed echocardiographic assessment of LV ejection fraction before and 6 months after PCI. Dobutamine stress echocardiography test was also performed before PCI. LV functional improvement was observed in 33/46 (72%) of patients. In patients with LV functional recovery in comparison with patients with no recovery, there was a significant difference in FFR before PCI (0.56 +/- 0.14 vs. 0.70 +/- 0.07, P < 0.001), improvement of FFR (0.35 +/- 0.14 vs. 0.21 +/- 0.07, P < 0.001), improvement of CFRthermo (1.3 +/- 0.6 vs. 0.5 +/- 0.3, P < 0.001), and CFRthermo after PCI (2.6 +/- 0.7 vs. 2.0 +/- 0.4, P < 0.001). When only parameters evaluated before PCI were taken into account, FFR before angioplasty (P = 0.001) and dobutamine-assessed viability (P = 0.006) were the most significant multivariate predictors of myocardial recovery. When all significant univariate parameters were evaluated, the most significant independent predictors for improvement in myocardial function were the improvement of CFRthermo during angioplasty (P < 0.001) and FFR before angioplasty (P = 0.002). Simultaneous evaluation of FFR and CFRthermo provide significant complementary data on the improvement in myocardial function in patients with previous MI. However, the evaluation of FFR before angioplasty identifies viable myocardium that may recover following revascularization and may be used as an alternative to non-invasive testing.

Effect of rapamycin therapy on coronary artery physiology early after cardiac transplantation

Rapamycin has been shown to reduce anatomical evidence of cardiac allograft vasculopathy, but its effect on coronary artery physiology is unknown. Twenty-seven patients without angiographic evidence of coronary artery disease underwent measurement of fractional flow reserve (FFR), coronary flow reserve (CFR), and the index of microcirculatory resistance (IMR) within 8 weeks and then 1 year after transplantation using a pressure sensor/thermistor-tipped guidewire. Measurements were compared between consecutive patients who were on rapamycin for at least 3 months during the first year after transplantation (rapamycin group, n = 9) and a comparable group on mycophenolate mofetil (MMF) instead (MMF group, n = 18). At baseline, there was no significant difference in FFR, CFR, or IMR between the 2 groups. At 1 year, FFR declined significantly in the MMF group (0.87 +/- 0.06 to 0.82 +/- 0.06, P = .009) but did not change in the rapamycin group (0.91 +/- 0.05 to 0.89 +/- 0.04, P = .33). Coronary flow reserve and IMR did not change significantly in the MMF group (3.1 +/- 1.7 to 3.2 +/- 1.0, P = .76; and 27.5 +/- 18.1 to 19.1 +/- 7.6, P = .10, respectively) but improved significantly in the rapamycin group (2.3 +/- 0.8 to 3.8 +/- 1.4, P < .03; and 27.0 +/- 11.5 to 17.6 +/- 7.5, P < .03, respectively). Multivariate regression analysis revealed that rapamycin therapy was an independent predictor of CFR and FFR at 1 year after transplantation. Early after cardiac transplantation, rapamycin therapy is associated with improved coronary artery physiology involving both the epicardial vessel and the microvasculature.

Abstract 3336: Fractional and Coronary Flow Reserve in Prediction of Functional Recovery of Myocardium in Patients with Previous Myocardial Infarction

Background: Fractional flow reserve (FFR) may provide clinically useful diagnostic information both in patients (pts) with normal left ventricular (LV) function as well as in pts with previous myocardial infarction (MI). However, the question remains to the relation between improvement of FFR and improvement of LV function in pts with previous MI undergoing percutaneous coronary intervention (PCI). Aim: The aim of the study was to evaluate the relation between FFR and simultaneously evaluated coronary flow reserve by thermodilution (CFRthermo), with functional improvement of LV function in pts with previous MI undergoing PCI. Methods: Study population consisted of 50 pts (mean age 53±8 years; 40 male) with previous MI and significant coronary stenosis in one-vessel CAD (33 LAD, 4 Cx, 13 RCA) undergoing PCI of infarct-related coronary artery. In all pts we have evaluated by single pressure/thermo wire FFR and CFRthermo before and immediately after PCI. In all pts, we have evaluated LV ejection fraction by echo and wall motion score index (WMSI) before and 3 months after PCI. Results: Coronary lesions were successfully treated in all pts with decrease of diameter stenosis from 63±7% to 18±9% (p&lt;0.001). FFR increased significantly (p&lt;0.001) from 0.62±0.15 to 0.91±0.06 after PCI, whereas CFRthermo increased significantly (p&lt;0.01) from 1.5±0.3 to 2.5±0.7. LV ejection fraction increased from 49±6% to 55±8% (p&lt;0.0001), and WMSI decreased from 1.44±0.24 to 1.29±0.29 (p&lt;0.0001). LV functional improvement was observed in 33/50 (66%) of pts. In pts with LV functional recovery in comparison to pts with no recovery there was significant difference in FFR before PCI (0.57±0.15 vs. 0.71±0.11, p=0.001), improvement of FFR during PCI (0.34±0.15 vs. 0.21±0.13, p=0.004), improvement of CFRthermo during PCI (1.2±0.6 vs. 0.6±0.5, p=0.001) and CFRthermo after PCI (2.7±0.7 vs. 2.1±0.6, p=0.008), respectively. Conclusion: Evaluation of FFR and CFRthermo provide significant prognostic information on LV functional recovery in pts with previous MI undergoing PCI. Lower FFR before PCI, higher CFRthermo after PCI, as well as higher improvement of FFR and CFRthermo during PCI are indicative of left ventricular functional improvement in pts with previous MI.

Intracoronary Continuous Adenosine Infusion A Novel and Effective Way of Inducing Maximal Hyperemia for Fractional Flow Reserve Measurement

Various methods are used to induce maximal hyperemia for physiologic studies, but the feasibility and efficacy of continuous intracoronary (IC) infusion of adenosine for measurement of fractional flow reserve (FFR) has not been well-defined. Patients with intermediate coronary artery stenosis were consecutively enrolled. In the phase I study, FFR was measured after 3 dosages of IC adenosine infusion (180, 240 and 300 microg/min) in 30 patients. The phase II study was performed to compare the hyperemic efficacy of IC infusion (240 microg/min) with IC bolus injection (40, 80 microg) and intravenous (IV) infusion (140 microg x kg (-1) x min(-1)) of adenosine in 20 patients. In the phase I study, no significant differences in FFR were observed with the 3 different doses of IC infusion (p = 0.06). In the phase II study, FFR after an IC bolus injection (0.83+/-0.06) was significantly higher than with IV (0.79+/-0.07) or IC (0.78+/-0.09) infusion (p < 0.01). However, no difference in FFR was observed for IC and IV infusions. IC infusion of adenosine seems to be a safe and effective method of inducing maximal hyperemia for FFR measurement.

Role of incremental doses of intracoronary adenosine for fractional flow reserve assessment

Background The achievement of maximal vasodilatation of the coronary microvessels is mandatory for the accurate determination of fractional flow reserve (FFR); the optimal dosing to achieve maximal vasodilation is unclear. This study was designed to address the hypothesis that incremental doses of intracoronary adenosine are necessary to ensure complete vasodilatation of the coronary microcirculation and accurate assessment of FFR. We also examined the relationship between FFR and coronary artery disease risk factors. Methods A total of 191 patients (215 vessels) with intermediate coronary lesions were examined. FFR was measured during cardiac catheterization with a pressure monitoring wire. Incremental doses of intracoronary adenosine (12–42 μg, left coronary artery; 12–48 μg, right coronary artery) were administered. Results Diabetes mellitus was present in 23% of patients, hypertension was present in 65% of patients, and prior myocardial infarction had occurred in 25% of patients. The average percent stenosis in vessels was 57% ± 15%. Vessels were subdivided on the basis of initial FFR (group 1, <0.75; group II, 0.75–0.79; group III, 0.80–0.89; group IV, ≥0.9). Five of the 24 (21%) vessels with an initial FFR in the 0.75 to 0.80 range had a subsequent FFR of <0.75. There was no difference in FFR or doses of adenosine in the patients with coronary artery disease risk factors. The average adenosine dose given at the achievement of minimal FFR was 26 μg in the right coronary artery (RCA) and 34 μg in the left coronary artery (LCA). The average maximum dose of intracoronary adenosine administered was 29 μg for the RCA and 37 μg for the LCA. The maximum dose of adenosine ever required to achieve minimum FFR was 42 μg in both the LCA and RCA. Conclusion This study suggests that a single high dose of 42 μg of intracoronary adenosine for both the RCA and LCA is sufficient to achieve maximum hyperemia and accurate FFR in most patients, independent of risk factors. Alternatively, when a lower initial dose is administered and FFR is in the 0.75 to 0.90 range, incremental doses of adenosine should be administered to ensure maximal hyperemia.

Adequacy of intracoronary versus intravenous adenosine-induced maximal coronary hyperemia for fractional flow reserve measurements

Background Fractional flow reserve (FFR) is a measure of coronary stenosis severity that is based on pressure measurements obtained at maximal hyperemia. The most widely used pharmacologic stimulus for maximal coronary hyperemia is adenosine, administered either as a continuous intravenous (IV) infusion or intracoronary (IC) bolus. IV adenosine has more side effects and is more costly than IC adenosine but has a more stable and prolonged hyperemic effect. Methods We compared the efficacy of IC and IV adenosine administration for the measurement of FFR in a multicenter trial. Fifty-two patients with 60 lesions underwent determination of FFR with both IV and IC adenosine. IV adenosine was administered as a continuous infusion at a rate of 140 μg/kg per minute until a steady state hyperemia was achieved. IC adenosine boluses were administered at a dose of 15 to 20 μg in the right and 18 to 24 μg in the left coronary artery. FFR was calculated as the ratio of the distal coronary pressure (from pressure guide wire) to the aortic pressure (guide catheter) at maximal hyperemia. Results A total of 26 left anterior descending, 23 right, 9 left circumflex, and 3 left main coronary arteries were evaluated. Mean percent stenosis for both groups was 55.8% ± 23.6% (range 0% to 95%), and mean FFR was 0.78 ± 0.15 (range 0.41 to 0.98). There was a strong and linear correlation between FFR measurements with IV and IC adenosine (R = 0.978, y = 0.032 + 0.964x, P < .001). The agreement between the 2 sets of measurements was also high, with a mean difference in FFR of –0.004 ± 0.03. However, a small random scatter in both directions of FFR measurements was noted with 5 lesions (8.3%) where FFR with IC adenosine was higher by 0.05 or more compared with IV infusions, suggesting a suboptimal hyperemic response in these patients. Changes in heart rate and blood pressure were significantly higher with IV adenosine. Two patients with IV, but none with IC adenosine, had severe side effects (bronchospasm and severe nausea). Conclusion These results suggest that IC adenosine is equivalent to IV infusion for the determination of FFR in the majority of patients. However, in a small percentage of cases, coronary hyperemia was suboptimal with IC adenosine. (Am Heart J 2000;140:651-7.)