Fractional flow reserve: intracoronary versus intravenous adenosine induced maximal coronary hyperemia

Comparison of efficacy and safety of intracoronary nicardipine and adenosine for fractional flow reserve assessment of coronary stenosis

BACKGROUND

Administration of intracoronary (IC) adenosine allows an easily feasible, inexpensive, and more rapid alternative method for fractional flow reserve (FFR). It is common practice in many centers worldwide. Nicardipine is a strong coronary vasodilator but its efficacy and safety for assessing FFR is not established. The purpose of present study was to compare the efficacy and safety of IC nicardipine and adenosine for assessing FFR.

METHODS

One hundred and fifty-nine patients with a total of 193 vessels undergoing clinically indicated FFR assessment of intermediate coronary stenoses were included. For the initial assessment of FFR, hyperemia was induced by an IC adenosine. After a washout period of 3 min, FFR was reassessed using 200 μg of IC nicardipine.

RESULTS

Hyperemic efficacy among two different stimuli was compared. The mean FFR with IC adenosine was 0.83 ± 0.09 and that with an IC nicardipine was 0.84 ± 0.09. The median FFR with an IC adenosine was 0.83 (0.78-0.91) and that with an IC nicardipine was 0.85 (0.79-0.91) (p-value 0.246). Both FFR values showed an excellent correlation (R² = 0.982, p < 0.001). Nicardipine produced fewer changes in heart rate, less chest pain and less flushing than adenosine. Transient atrioventricular block occurred in 29 patients with IC adenosine and none with IC nicardipine.

CONCLUSIONS

IC bolus injection of nicardipine could be introduced as a safe and practical alternative method of inducing hyperemia during FFR measurements. Compared to IC adenosine, IC nicardipine has a similar hyperemic efficacy and excellent side-effect profile.

Individual Lesion-Level Meta-Analysis Comparing Various Doses of Intracoronary Bolus Injection of Adenosine With Intravenous Administration of Adenosine for Fractional Flow Reserve Assessment

BACKGROUND

Intravenous infusion of adenosine is considered standard practice for fractional flow reserve (FFR) assessment but is associated with adverse side-effects and is time-consuming. Intracoronary bolus injection of adenosine is better tolerated by patients, cheaper, and less time-consuming. However, current literature remains fragmented and modestly sized regarding the equivalence of intracoronary versus intravenous adenosine. We aim to investigate the relationship between intracoronary adenosine and intravenous adenosine to determine FFR.

METHODS

We performed a lesion-level meta-analysis to compare intracoronary adenosine with intravenous adenosine (140 µg/kg per minute) for FFR assessment. The search was conducted in accordance to the Preferred Reporting for Systematic Reviews and Meta-Analysis statement. Lesion-level data were obtained by contacting the respective authors or by digitization of scatterplots using custom-made software. Intracoronary adenosine dose was defined as; low: <40 µg, intermediate: 40 to 99 µg, and high: ≥100 µg.

RESULTS

We collected 1972 FFR measurements (1413 lesions) comparing intracoronary with intravenous adenosine from 16 studies. There was a strong correlation (correlation coefficient =0.915; P<0.001) between intracoronary-FFR and intravenous-FFR. Mean FFR was 0.81±0.11 for intracoronary adenosine and 0.81±0.11 for intravenous adenosine (P<0.001). We documented a nonclinically relevant mean difference of 0.006 (limits of agreement: -0.066 to 0.078) between the methods. When stratified by the intracoronary adenosine dose, mean differences between intracoronary and intravenous-FFR amounted to 0.004, 0.011, or 0.000 FFR units for low-dose, intermediate-dose, and high-dose intracoronary adenosine, respectively.

CONCLUSIONS

The present study documents clinically irrelevant differences in FFR values obtained with intracoronary versus intravenous adenosine. Intracoronary adenosine hence confers a practical and patient-friendly alternative for intravenous adenosine for FFR assessment.

Intracoronary versus intravenous adenosine to assess fractional flow reserve: a systematic review and meta-analysis

AIMS

Intravenous infusion of adenosine is the reference method to measure fractional flow reserve (FFR). Intracoronary boluses are often used because of time and convenience, but their effectiveness has yet to be assessed.

METHODS

We conducted a systematic review and meta-analysis of prospective studies directly comparing intravenous and intracoronary adenosine administration for FFR measurement. FFR values and prevalence of functionally critical lesions obtained with the different methods of adenosine administration were compared.

RESULTS

Twelve studies evaluating 781 lesions from 731 patients were included (63.7 years, 25.5% women, median FFR 0.82). FFR values were significantly lower with intravenous adenosine than with intracoronary adenosine [mean difference 0.01, 95% confidence interval (CI) 0.00-0.02, P = 0.005], even if no significant differences were observed when only high doses of intracoronary adenosine (≥150 μg) were considered. The prevalence of functionally critical lesions did not significantly differ between intracoronary and intravenous adenosine. Concerning the use of different doses of intracoronary adenosine, low doses (≤60 μg) were associated with higher FFR values (mean difference 0.02, 95% CI 0.01-0.03, P < 0.001) and fewer functionally critical lesions (OR 0.57, 95% CI 0.40-0.81, P = 0.002) compared with high doses. Meta-regression analysis did not show any significant interaction between the way of adenosine administration and main clinical features. Intracoronary adenosine was associated with a higher incidence of atrioventricular blocks, whereas angina and/or systemic symptoms were more frequent with intravenous adenosine.

CONCLUSION

Intracoronary adenosine might be as effective as intravenous adenosine to measure FFR, provided that adequate doses are used. Intracoronary adenosine represents a valuable alternative to intravenous adenosine whenever appropriately administered.

Meta-Analysis of Head-to-Head Comparison of Intracoronary Versus Intravenous Adenosine for the Assessment of Fractional Flow Reserve

Intravenous (IV) infusion of adenosine represents the gold standard for measuring fractional flow reserve (FFR). However, IV adenosine is more expensive and time-consuming compared with intracoronary (IC) boluses of adenosine. We conducted a meta-analysis of studies comparing IC with IV adenosine for FFR assessment in the same coronary lesions. We searched for studies comparing IC with IV adenosine and reporting absolute FFR values or rate of abnormal FFR for both routes. Prespecified subgroup analysis was performed to appraise studies using low-dose (<100 μg) or high-dose IC adenosine (≥100 μg). We retrieved 11 studies amounting to 587 patients and 621 lesions. Six studies evaluated low-dose IC boluses (15 to 80 μg) and 5 studies high-dose boluses (120 to 600 μg). Absolute FFR values were slightly, yet significantly lower with IV adenosine compared with IC adenosine (mean difference 0.02, 95% confidence interval [CI] 0.00 to 0.03, p = 0.02). This difference, however, did not translate into a significant difference in the rate of abnormal FFR between IC and IV adenosine (hazard ratio 0.93, 95% CI 0.76 to 1.13, p = 0.57); moreover, no statistically significant difference was observed between low-dose and high-dose IC adenosine subgroups. Adverse events were less frequent with IC adenosine compared with IV adenosine (risk ratio 0.17, 95% CI 0.07 to 0.43, p <0.001). In conclusion, IC administration of adenosine, although inducing a slightly lower amount of hyperemia compared with IV infusion of adenosine, yields a similar diagnostic accuracy in identifying hemodynamically significant coronary stenosis and is better tolerated by the patients.

Assessment of increasing intravenous adenosine dose in fractional flow reserve

Background

Effects of increased adenosine dose in the assessment of fractional flow reserve (FFR) were studied in relation to FFR results, hemodynamic effects and patient discomfort. FFR require maximal hyperemia mediated by adenosine. Standard dose is 140 μg/kg/min administrated intravenously. Higher doses are commonly used in clinical practice, but an extensive comparison between standard intravenous dose and a high dose (220 μg/kg/min) has previously not been performed.

Methods

Seventy-five patients undergoing FFR received standard dose adenosine, followed by high dose adenosine. FFR, mean arterial pressure (MAP) and heart rate (HR) were analyzed. Patient discomfort measured by Visual Analogue Scale (VAS) was assessed.

Results

No significant difference was found between the doses in FFR value (0.85 [0.79–0.90] vs 0.85 [0.79–0.89], p = 0.24). The two doses correlated well irrespective of lesion severity (r = 0.86, slope = 0.89, p = <0.001). There were no differences in MAP or HR. Patient discomfort was more pronounced using high dose adenosine (8.0 [5.0–9.0]) versus standard dose (5.0 [2.0–7.0]), p = <0.001.

Conclusions

Increased dose adenosine does not improve hyperemia and is associated with increased patient discomfort. Our findings do not support the use of high dose adenosine.

Trial registration

Retrospective Trial registration: Current Controlled Trials ISRCTN14618196. Registered 15 December 2016.

Differences between automatically detected and steady-state fractional flow reserve

BACKGROUND

Measurement of fractional flow reserve (FFR) has become a standard diagnostic tool in the catheterization laboratory. FFR evaluation studies were based on pressure recordings during steady-state maximum hyperemia. Commercially available computer systems detect the lowest Pd/Pa ratio automatically, which might not always be measured during steady-state hyperemia. We sought to compare the automatically detected FFR and true steady-state FFR.

METHODS AND RESULTS

Pressure measurement traces of 105 coronary lesions from 77 patients with intermediate coronary lesions or multivessel disease were reviewed. In all patients, hyperemia had been achieved by intravenous adenosine administration using a dosage of 140 µg/kg/min. In 42 lesions (40%) automatically detected FFR was lower than true steady-state FFR. Mean bias was 0.009 (standard deviation 0.015, limits of agreement -0.02, 0.037). In 4 lesions (3.8%) both methods lead to different treatment recommendations, in all 4 cases instantaneous wave-free ratio confirmed steady-state FFR.

CONCLUSIONS

Automatically detected FFR was slightly lower than steady-state FFR in more than one-third of cases. Consequently, interpretation of automatically detected FFR values closely below the cutoff value requires special attention.