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Published on: May 28, 2019
Interpretation of fractional flow reserve in ST-elevation myocardial infarction culprit lesions
Stephen P Hoole1, Adam J Brown, Catherine Jaworski
1Department of Interventional Cardiology, Papworth Hospital, Papworth Everard, Cambridge, UK.
Insights
Fractional flow reserve (FFR) can assess ST-elevation myocardial infarction (STEMI) culprit lesions when microcirculatory function is preserved. This study found that FFR is feasible for evaluating haemodynamically significant lesions in STEMI patients with initially normal microcirculation.
Area of Science:
- Cardiology
- Interventional Cardiology
- Microcirculation Research
Background:
- Pressure wire assessment of the infarct-related artery (IRA) in ST-elevation myocardial infarction (STEMI) is typically delayed until microcirculatory dysfunction resolves.
- Understanding microcirculatory impact on haemodynamics is crucial for STEMI management.
Purpose of the Study:
- To evaluate serial fractional flow reserve (FFR) and index of microcirculatory resistance (IMR) in the IRA of STEMI patients.
- To improve the interpretation of FFR measurements during primary percutaneous coronary intervention (PPCI).
Main Methods:
- Forty-one STEMI patients undergoing PPCI were assessed using a pressure wire.
- Measurements were taken at baseline after thrombectomy and post-stenting.
Main Results:
- Most STEMI culprit lesions were haemodynamically significant (mean FFR pre-PPCI: 0.54±0.20).
- Culprit lesion FFR correlated with initial IMR (r=0.45, P=0.004).
- Patients with normal initial IMR (<25) had lower FFR despite milder stenoses, but IMR improved during PPCI.
Conclusions:
- STEMI culprit lesions demonstrate significant haemodynamic impact.
- A subset of STEMI IRAs exhibits preserved microcirculatory function, allowing for feasible FFR assessment of culprit stenosis.
Background:
Pressure wire assessment of the infarct-related artery (IRA) in ST-elevation myocardial infarction (STEMI) is not recommended until microcirculatory dysfunction recovers.
Objective:
The objective of this study was to assess serial fractional flow reserve (FFR) and the index of microcirculatory resistance (IMR) in the IRA of STEMI patients to better understand and interpret FFR during primary percutaneous coronary intervention (PPCI).
Methods:
Forty-one patients undergoing PPCI for STEMI were studied with a pressure wire at baseline after thrombectomy and after stenting.
Results:
The majority of STEMI culprit lesions in the IRA were haemodynamically significant (mean FFR pre-PPCI: 0.54±0.20); only 4/41 culprit lesions had FFR greater than 0.80. The FFR of the culprit lesion and the initial IMR were correlated (r=0.45, P=0.004). Patients with a normal initial IMR of less than 25 exhibited lower culprit lesion FFR values (0.47±0.20 vs. 0.60±0.18, P=0.03) despite milder angiographic stenoses [angiographic stenoses (%): 80.4±10.4 vs. 86.6±8.0, P=0.03] but showed a reduction in the IMR during PPCI (pre-PPCI: 16.9±5.7 vs. post-PPCI: 32.2±22.6, P=0.009).
Conclusion:
STEMI culprit lesions are haemodynamically significant. A subset of STEMI IRAs has initially preserved microcirculatory function; thus, the culprit stenosis may feasibly be assessed through FFR.
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