Author + information
- Sergio Baptista1,
- Mariana Faustino1,
- Luis Brizida1,
- Jose Loureiro2,
- Antonio Freitas1,
- João Augusto1,
- João Abecasis3,
- Célia Monteiro1,
- Paulo Leal1,
- Maura Nedio1,
- Cláudia Antunes1,
- Pedro Farto e Abreu1,
- Victor Gil1 and
- Carlos Morais1
The index of microcirculatory resistance (IMR) is an invasive surrogate of coronary microvascular function and and an early marker of cardiac recovery, after acute ST elevation myocardial infarction (STEMI), as evaluated by echocardiography. Our purpose in the current study was to confirm its relation with infarct extension (IE) and microvascular obstruction (MVO), measured by several different methods, in patients with STEMI treated by primary percutaneous coronary intervention (P-PCI).
IMR was measured immediately after successful P-PCI, with a pressure-wire. IE was evaluated by contrast enhanced cardiac magnetic resonance (ceCMR), echocardiography and troponin release. MVO was evaluated by ceCMR, angiographic indicators (corrected TIMI frame count and TIMI myocardial perfusion grade) and ECG ST resolution.
60 patients were included. Infarct extension and MVO were evaluated according to the median IMR value (23.9 [IQR 32.9]). The results for infarct extension are presented in the Table. IMR >24 was associated with higher prevalence of MVO (45.0% vs. 13.8%, p=0.015) and with higher MVO mass (median/IQR 6.4/11.5 vs 2.9/2.9, p=0.006) in the ceCMR. Indirect indicators of MVO (cTFC: median/IQR 2.0/10.0 vs. 14.0/7.0, p<0.001; TMPG 2 or 3: 70.0% vs. 93.3%, p=0.019; 90 min ECG ST resolution: median/IQR 75.5/36.0 vs. 86.5/29.0, p=0.014) were also worst in these patients. The ROC analysis of IMR to predict MVO showed an AUC of 0.723 (CI 95% 0.500-0.896, p=0.018). The optimal IMR cutoff value for predicting MVO was 33 (sensitivity 69.2%; specificity 80.6%). Patients with higher IMR had a higher incidence of the combined endpoint of cardiovascular major events, heart failure and hospital admissions (6.9% vs. 30.0%, p=0.024).
|Variable||Total Population (n=60)||IMR>24||p value|
|No (n=30)||Yes (n=30)|
|Global longitudinal strain||-15.77±3.11||-16.81±1.86||-14.50±3.83||0.007|
|ceCMR||Transmural necrosis||23 (46.9)||8 (27.6)||15 (75.0)||0.001|
|Total infarct mass||14.7 (12.6)||11.4 (10.9)||17.6 (15.0)||0.031|
|Percent infarct mass||12.6 (14.4)||11.6 (12.1)||17.0 (15.4)||0.035|
IMR evaluated immediately after P-PCI in patients with STEMI predicts both myocardial infarction extension and MVO, identifying patients with worst prognosis.
CORONARY: Acute Myocardial Infarction