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Single-view angiographic microcirculatory resistance index after primary PCI: the EARLY-MYO-AMR study
Zhiwen Zhang1, Song Ding2, Quan Guo1
1Department of Coronary Heart Disease, Fuwai Central China Cardiovascular Hospital, Henan Key Laboratory of Coronary Heart Disease Control & Prevention, Henan Provincial Clinical Research Center for Cardiovascular Disease, Central China Fuwai of Zhengzhou University, Zhengzhou, China.
Background:
Coronary microvascular dysfunction (CMD) leads to inadequate myocardial perfusion in patients with ST-segment elevation myocardial infarction (STEMI) undergoing primary percutaneous coronary intervention (PPCI). The index of microcirculatory resistance (IMR) is an intraoperative diagnostic tool for CMD. However, its widespread application is hindered by the requirement for pressure wires and hyperaemic agents. The angiographic microcirculatory resistance (AMR) index is concise, convenient, accurate, and serves as a pressure wire-free alternative to the IMR.
Aims:
This study aimed to demonstrate the ability of AMR to detect CMD in patients with STEMI undergoing PPCI therapy and to assess its predictive value for long-term prognosis.
Methods:
The EARLY-MYO-AMR trial comprised two cohorts. The derivation cohort included 495 patients with STEMI who underwent PPCI within 12 h and cardiac magnetic resonance (CMR) within 14 days of symptom onset. The optimal AMR cutoff value for diagnosing CMD using CMR was determined by analysing the receiver operating characteristic curves. The validation cohort enrolled 2,663 patients with STEMI who underwent PPCI within 12 h of symptom onset from January 2012 to April 2022 across 5 medical centres. All patients were followed up for at least 1 year. The primary endpoint was the occurrence of major adverse cardiovascular events (MACE), including cardiac death, hospitalisation for heart failure, repeat myocardial infarction, and target lesion revascularisation.
Results:
The derivation cohort identified an AMR cutoff >26.6 mmHg*s/dm for predicting CMD post-PPCI (area under the curve 0.721, 95% confidence interval [CI]: 0.677-0.763). Multivariable logistic regression analysis indicated that AMR >26.6 mmHg*s/dm was a CMD risk factor (odds ratio 4.10, 95% CI: 2.56-6.56; p<0.001). The MACE incidence was significantly higher among patients in the validation cohort with AMR >26.6 mmHg*s/dm than among those with AMR ≤26.6 mmHg*s/dm (30.9% vs 21.5%, adjusted hazard ratio [HR] 1.47, 95% CI: 1.20-1.80; p<0.001). MACE incidence increased with AMR, with an adjusted HR of 1.30 (95% CI: 1.17-1.46; p<0.001) per 10 mmHg*s/dm increase. The Bland-Altman and Kappa analyses showed good intra- and interobserver agreement for AMR (intraobserver: bias=-0.104, k=0.914; interobserver: bias=-0.032, k=0.958).
Conclusions:
AMR >26.6 mmHg*s/dm predicts CMD during PPCI and increased MACE incidence in patients with STEMI. This convenient tool helps in risk stratification and treatment guidance for STEMI prognosis.
Insights
The novel angiographic microcirculatory resistance (AMR) index effectively identifies coronary microvascular dysfunction (CMD) in ST-elevation myocardial infarction (STEMI) patients. Higher AMR values predict increased major adverse cardiovascular events (MACE) after primary percutaneous coronary intervention (PPCI).
Area of Science:
- Cardiology
- Interventional Cardiology
- Cardiovascular Imaging
Background:
- Coronary microvascular dysfunction (CMD) impairs myocardial perfusion in ST-segment elevation myocardial infarction (STEMI) patients undergoing primary percutaneous coronary intervention (PPCI).
- The index of microcirculatory resistance (IMR) is a diagnostic tool for CMD but requires pressure wires and hyperemic agents.
- Angiographic microcirculatory resistance (AMR) offers a pressure wire-free, convenient alternative to IMR for assessing CMD.
Purpose of the Study:
- To evaluate the efficacy of AMR in detecting CMD in STEMI patients undergoing PPCI.
- To assess the predictive capability of AMR for long-term adverse cardiovascular outcomes.
Main Methods:
- The EARLY-MYO-AMR trial included derivation (n=495) and validation (n=2,663) cohorts of STEMI patients treated with PPCI.
- Cardiac magnetic resonance (CMR) was used to determine the optimal AMR cutoff for CMD diagnosis in the derivation cohort.
- Patients were followed for at least 1 year to track major adverse cardiovascular events (MACE).
Main Results:
- An AMR cutoff >26.6 mmHg*s/dm was identified for predicting CMD (AUC 0.721) and was an independent risk factor (OR 4.10).
- In the validation cohort, AMR >26.6 mmHg*s/dm was associated with significantly higher MACE incidence (30.9% vs. 21.5%; aHR 1.47).
- MACE incidence increased progressively with higher AMR values, showing good intra- and interobserver agreement.
Conclusions:
- AMR >26.6 mmHg*s/dm effectively predicts CMD in STEMI patients undergoing PPCI.
- Elevated AMR is linked to increased long-term MACE, aiding in risk stratification.
- AMR serves as a valuable, convenient tool for guiding treatment and improving prognosis in STEMI.
