What is the clinical evidence from this study?

Study design: RCT. Population: ST-segment elevation myocardial infarction (STEMI) with concurrent chronic total occlusion (CTO) (n=180). Intervention: CTO PCI vs. no-CTO PCI. Primary outcome: Change in segmental wall thickening (SWT) in dysfunctional segments of the CTO territory from baseline to 4 months (p=0.03).

December 1, 2016Open Access

Improved recovery of regional left ventricular function after PCI of chronic total occlusion in STEMI patients: a cardiovascular magnetic resonance study of the randomized controlled EXPLORE trial

Key Result

CTO PCI compared with no-CTO PCI resulted in a significantly greater recovery of segmental wall thickening in dysfunctional segments of the CTO territory (17% vs 11%, p=0.03) at 4 months.

Study Design

Type

RCT (n=180)

Blinding

Single-blind

Randomization

1:1

Multicenter

Yes

PICO

Population

ST-segment elevation myocardial infarction (STEMI) with concurrent chronic total occlusion (CTO) (n=180)

Intervention / Comparator

CTO PCI vs no-CTO PCI (within 7 days after primary PCI)

Primary Outcome

Change in segmental wall thickening (SWT) in dysfunctional segments of the CTO territory from baseline to 4 months, p=0.03

Main Result

Absolute Event Rate: 17% vs 11%

p-value: p=0.03

Limitations

Sample size might be too small to detect differences, especially in the various subgroups
Baseline CMR was not performed in all patients included in the main EXPLORE trial
Results might not be applicable to patients with severely reduced LVEF or cardiogenic shock

Abstract

BACKGROUND: The Evaluating Xience and left ventricular function in PCI on occlusiOns afteR STEMI (EXPLORE) trial did not show a significant benefit of percutaneous coronary intervention (PCI) of the concurrent chronic total occlusion (CTO) in ST-segment elevation myocardial infarction (STEMI) patients on global left ventricular (LV) systolic function. However a possible treatment effect will be most pronounced in the CTO territory. Therefore, we aimed to study the effect of CTO PCI compared to no-CTO PCI on the recovery of regional LV function, particularly in the CTO territory. METHODS: Using cardiovascular magnetic resonance (CMR) we studied 180 of the 302 EXPLORE patients with serial CMR (baseline and 4 months follow-up). Segmental wall thickening (SWT) was quantified on cine images by an independent core laboratory. Dysfunctional segments were defined as SWT < 45%. Dysfunctional segments were further analyzed by viability (transmural extent of infarction (TEI) ≤50%.). All outcomes were stratified for randomization treatment. RESULTS: In the dysfunctional segments in the CTO territory recovery of SWT was better after CTO PCI compared to no-CTO PCI (ΔSWT 17 ± 27% vs 11 ± 23%, p = 0.03). This recovery was most pronounced in the dysfunctional but viable segments(TEI < 50%) (ΔSWT 17 ± 27% vs 11 ± 22%, p = 0.02). Furthermore in the CTO territory, recovery of SWT was significantly better in the dysfunctional segments in patients with Rentrop grade 2-3 collaterals compared to grade 0-1 collaterals to the CTO (16 ± 26% versus 11 ± 24%, p = 0.04). CONCLUSION: CTO PCI compared with no-CTO PCI is associated with a greater recovery of regional systolic function in the CTO territory, especially in the dysfunctional but viable segments. Further research is needed to evaluate the use of CMR in selecting post-STEMI patients for CTO PCI and the effect of regional LV function recovery on clinical outcome. TRIAL REGISTRATION: Trialregister.nl NTR1108 , Date registered NTR: 30-okt-2007.

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