RESUMO
Background: The recommended dosage of intracoronary adenosine in fractional flow reserve (FFR) assessment is controversial. High-dose adenosine may overcome the biological variability of adenosine response in hyperemia. Objectives: We aimed to test the efficacy and safety of a high-dose escalation protocol at our institute. Methods: Using the adenosine dose escalation protocol, the percentages of FFR ≤ 0.75 and 0.80 after high-dose escalation were compared with those at conventional doses. The chi-squared test was used to evaluate the accuracy of FFR values with the tested doses by comparing them with the results of a non-invasive pretest. Results: A total of 87 patients (130 vessels) were included, and protocol adherence was 93.1%. High-dose intracoronary adenosine was injected in 78.5% of the vessels. The dose escalation strategy was well-tolerated without serious complications. The positive rate increased significantly after conducting the protocol compared to that with a conventional dose (28.2% vs. 23.6% with an FFR threshold of 0.75, and 48.7% vs. 42.5% with a threshold of 0.80, both p < 0.05). In the validation cohort, only FFR ≤ 0.75 was associated with the binary result of the non-invasive pretest (p < 0.01 vs. p = 0.37). The high-dose adenosine escalation strategy did not increase the accuracy of FFR (77.8% vs. 75.6% in conventional dose and high-dose adenosine, respectively). Conclusions: The use of a high-dose escalation strategy increased the positive rate in FFR assessments.
RESUMO
Maximal hyperaemia for fractional flow reserve (FFR) may not be achieved with the current recommended doses of intracoronary adenosine. Higher doses (up to 720 µg) have been reported to optimize hyperaemic stimuli in small dose-response studies. Real-world data from a large cohort of patients is needed to evaluate FFR results and the safety of high-dose escalation. This is a retrospective study aimed to evaluate the safety and frequency of FFR ≤0.8 after high-dose escalation of intracoronary adenosine. Data were extracted from the medical databases of two university hospitals. Increasing doses (100, 200, 400, 600, and 800 µg) of adenosine were administered as intracoronary boluses until FFR ≤0.8 was achieved or heart block developed. The percentage of FFR ≤0.8 after higher-dose escalation was compared with those at conventional doses, and the predictors for FFR ≤0.8 after higher doses were analysed. In the 1163 vessels of 878 patients, 402 vessels (34.6%) achieved FFR ≤0.8 at conventional doses and 623 vessels (53.6%) received high-dose escalation. An additional 84 vessels (13.5%) achieved FFR ≤0.8 after high-dose escalation. No major complications developed during high-dose escalation. Borderline FFR (0.81-0.85) at the conventional dose, stenosis >60%, and triple-vessel disease increased the likelihood of FFR ≤0.8 after high-dose escalation, but chronic kidney disease decreased it. For vessels of borderline FFR at conventional doses, 46% achieved FFR ≤0.8 after high-dose escalation. In conclusion, High-dose escalation of intracoronary adenosine increases the frequency of FFR ≤0.8 without major complications. It could be especially feasible for borderline FFR values near the 0.8 diagnostic threshold.