Functional Assessment of Lesions: Advances with MRI

Computer tomography (CT) had taken over in the race to develop software capable of measuring FFR non-invasively. Magnetic resonance imaging (MRI) wouldn’t fall behind and has also tried non-inferiority vs an FFR based strategy, according to this study recently published in the prestigious NEJM, called MR-INFORM.

In patients with chronic angina and CAD risk factors, MR perfusion was associated to lower revascularization incidence, and also resulted non-inferior compared to FFR as regards major cardiac events.

All evidence (and guidelines alongside) points to ischemia driven revascularization. Anatomy lags making room to function, when it comes to deciding for or against revascularization. Obviously, once the decision has been made, tools such as IVUS or OCT are extremely useful for strategy planning. In fact, IVUS in particular has shown to reduce mortality when guiding PCI, and this is especially true for left main lesions.

The MR-INFORM randomized 918 patients with typical angina and at least two cardiovascular risk factors or a positive stress test to MR based strategy vs. FFR based strategy.

Read also: TCT 2018 | ULTIMATE: IVUS Guided DES Implantation for All Vessels, for All Lesions.

Revascularization was recommended for patients with at least 6% ischemia in MRI or in 0.8 or lower FFR.

Primary end point was a composite of death, non-fatal infarction or target vessel revascularization at one year. Non-inferiority cutoff value was a risk difference of 6%.

A total 184 over 454 (40.5%) in the MRI group and 213 of 464 in the FFR group (45.9%) met the criteria to recommend revascularization (p=0.11), though the MRI group saw fewer revascularizations (35.7% vs 45%; p=0.005).

Read also: The use of IVUS in unprotected left main PCI associated to better outcomes, compared to angiography guided PCI.

Primary end point occurred in 3.6% of patients in the MRI group vs. 3.7% in the FFR guided group; with these figures the MRI based strategy reached non-inferiority.

At one year, the percentage of patients free from angina resulted similar between the groups (49.2% in the MRI group vs 43.8% in the FFR).

Conclusion

In patients with chronic stable angina and CAE risk factors, myocardial perfusion cardiovascular MRI was associated with lower revascularization rate compared against the FFR based strategy and, in addition, MRI resulted non-inferior in major cardiovascular events.

Original Title: Magnetic Resonance Perfusion or Fractional Flow Reserve in Coronary Disease.

Reference: Eike Nagel et al. N Engl J Med 2019;380:2418-28.

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