iFR-SWEDEHEART: iFR vs FFR-Guided Coronary Revascularisation
Reported from TCT 2021
Nicola Ryan reviews the iFR Swedeheart multicenter, randomized, controlled, open-label clinical trial using the Swedish Coronary Angiography and Angioplasty Registry (SCAAR) for enrolment randomisation and follow up. At one year follow up iFR guided revascularisation was shown to be non-inferior to FFR guided revascularisation, these results persisted at two-years. Here the authors present the five year follow up data.
Why this study – the rationale/objective?
iFR is a non-hyperaemic index for the assessment of coronary lesion severity, prior to iFR Swedeheart validation studies had shown similar ability to detect ischaemia compared with FFR. iFR Swedeheart aimed to test the hypothesis that iFR was non-inferior to FFR regarding a composite endpoint of all cause death, MI and unplanned revascularisation. At one year iFR was non-inferior to FFR (iFR 6.7% vs FFR 6.1%, HR 1.12, 95% CI 0.79-1.58, p=0.53) regarding the composite primary endpoint. This analysis reports the longer term outcomes to 5-years.
How was it executed - the methodology?
From May 2014-October 2015, 2037 patients presenting with stable angina, unstable angina or NSTEMI with an indication for physiological assessment of a coronary lesion (visually 40-80% stenosis) were enrolled. 1019 patients were randomised to iFR guided revascularisation and 1018 to FFR guided revascularisation. Follow up through 5-years was obtained through SCAAR (registry based randomised clinical trial).
- The primary end point was the rate of a composite of death from any cause, nonfatal myocardial infarction, or unplanned revascularization within 12 months after the procedure.
- Secondary endpoints included assessment of death, non-fatal MI and unplanned revascularization separate and in any combination after 30 days, 1, 2, 3, 4 and 5 years
What is the main result?
- The primary endpoint occurred in 21.5% of patients in the iFR group compared to 19.9% in the FFR group (HR 1.09, 95% CI 0.90-1.33) at five years.
- At 5-years there was no difference in all-cause mortality between the two groups (iFR 9.4% vs FFR 7.9%, HR 1.2, 95% CI 0.89-1.62)
- Rates of non-fatal MI were similar at 5 years (iFR 5.8% vs. FFR 5.7%, HR 1.0, 95% CI 0.70-1.44), with no differences in unplanned revascularisation (iFR 11.6% vs. FFR 11.3%, HR 1.02, 95% CI 0.79-1.32)
- Prespecified subgroup analysis including assessment by gender, age and diabetes did not show any difference in outcome in any subgroups.
Critical reading and the relevance for clinical practice
It must be understood that the 5-year results of iFR Swedeheart have yet to be published therefore the following assumptions are based upon the presented data.
The results of this multicenter, randomized, controlled, open-label clinical trial confirm the long term safety and efficacy of iFR guided revascularisation compared to FFR guided revascularisation in patients presenting with stable angina, unstable angina or NSTEMI with an indication for physiological assessment of a coronary lesion.
The longer term outcome was of particular interest given that the FFR group had more functionally significant lesions than the iFR group (36.8% vs. 29.2%, p<0.0001) however increased deferral with iFR did not lead to higher rates of MI or unplanned revascularisation. Whilst initially a dichotomous index future trials will look to optimising PCI based upon assessment of the iFR pullback gradients of the entire vessel as well as post PCI iFR.
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