What is the clinical evidence from this study?

Study design: Observational. Population: Acute Myocardial Infarction (n=42). Intervention: Time after acute myocardial infarction vs. Baseline (4-6 days post-AMI). Primary outcome: Native T1 of remote myocardium (p=<0.01).

June 23, 2017Open Access

Changes in remote myocardial tissue after acute myocardial infarction and its relation to cardiac remodeling: A CMR T1 mapping study

Q: What are the key findings of this study?

In patients with reperfused acute myocardial infarction, native T1 of remote myocardium significantly decreased from 1002 ms at baseline to 985 ms at 3 months, suggesting resolution of remote edema.

Resultado clave

In patients with reperfused acute myocardial infarction, native T1 of remote myocardium significantly decreased from 1002 ms at baseline to 985 ms at 3 months, suggesting resolution of remote edema.

Diseño del estudio

Tipo

Observational (n=42)

Multicéntrico

PICO estructurado

Población

42 patients (mean age 60 years, 19% female) with acute ST-segment elevation myocardial infarction successfully treated with primary PCI, evaluated with CMR at 4-6 days and 3 months.

Resultado

Temporal alterations in native T1 and extracellular volume (ECV) of remote myocardium from baseline (4-6 days) to 3 months follow-up, and their relation to left ventricular (LV) remodeling (LV dilatation defined as an increase in LV end-diastolic volume of ≥15%).surrogate

In patients with reperfused first-time AMI, native T1 of remote myocardium decreases over 3 months, while persistently elevated remote extracellular volume is associated with left ventricular dilatation.

Resultado numérico

Tasa de eventos absoluta: 985% vs 1002%

valor p: p=<0.01

Limitaciones

Relatively small sample size
Use of synthetic ECV instead of conventional ECV with hematocrit sampling
Lack of measurement of other inflammatory markers like interleukins and tumor necrosis factors
Lack of longer follow-up

Resumen

OBJECTIVES: To characterize the temporal alterations in native T1 and extracellular volume (ECV) of remote myocardium after acute myocardial infarction (AMI), and to explore their relation to left ventricular (LV) remodeling. METHODS: Forty-two patients with AMI successfully treated with primary PCI underwent cardiovascular magnetic resonance after 4-6 days and 3 months. Cine imaging, late gadolinium enhancement, and T1-mapping (MOLLI) was performed at 1.5T. T1 values were measured in the myocardial tissue opposite of the infarct area. Myocardial ECV was calculated from native- and post-contrast T1 values in 35 patients, using a correction for synthetic hematocrit. RESULTS: Native T1 of remote myocardium significantly decreased between baseline and follow-up (1002 ± 39 to 985 ± 30ms, p<0.01). High remote native T1 at baseline was independently associated with a high C-reactive protein level (standardized Beta 0.32, p = 0.04) and the presence of microvascular injury (standardized Beta 0.34, p = 0.03). ECV of remote myocardium significantly decreased over time in patients with no LV dilatation (29 ± 3.8 to 27 ± 2.3%, p<0.01). In patients with LV dilatation, remote ECV remained similar over time, and was significantly higher at follow-up compared to patients without LV dilatation (30 ± 2.0 versus 27 ± 2.3%, p = 0.03). CONCLUSIONS: In reperfused first-time AMI patients, native T1 of remote myocardium decreased from baseline to follow-up. ECV of remote myocardium decreased over time in patients with no LV dilatation, but remained elevated at follow-up in those who developed LV dilatation. Findings from this study may add to an increased understanding of the pathophysiological mechanisms of cardiac remodeling after AMI.

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