Author + information
- Joëlle Elias, MD,
- Loes P. Hoebers, MD, PhD,
- Ivo M. van Dongen, MD,
- Bimmer E.P.M. Claessen, MD, PhD,
- René J. van der Schaaf, MD, PhD,
- Jan G. Tijssen, PhD,
- Alexander Hirsch, MD, PhD,
- José P.S. Henriques, MD, PhD∗ (, )
- EXPLORE Investigators
- ↵∗Department of Cardiology, Academic Medical Center – University of Amsterdam, Meibergdreef 9, 1105 AZ Amsterdam, the Netherlands
In ST-segment elevation myocardial infarction (STEMI) patients with a concurrent chronic total occlusion (CTO), the EXPLORE (Evaluating Xience and Left Ventricular Function in Percutaneous Coronary Intervention on Occlusions After ST-Elevation Myocardial Infarction) trial (n = 302) was the first randomized trial comparing CTO percutaneous coronary intervention (PCI) versus no-CTO PCI. This study showed that CTO PCI compared to no-CTO PCI did not result in a better left ventricular (LV) function at 4-month follow-up cardiac magnetic resonance imaging (CMR) (1). Despite the neutral effect on LV function, a significant interaction in patients with a CTO in the left anterior descending artery (LAD) was seen (CTO PCI vs. no-CTO PCI: 47.2 ± 12.3% vs. 40.4 ± 11.9%; p = 0.02). This implies that the effect of CTO PCI might vary according to the CTO location. However, in-depth analysis of recovery (baseline to 4 months) was not performed. Therefore, we used serial CMR (n = 180) to evaluate the impact of CTO location on the effect of CTO PCI compared to no-CTO PCI on LV recovery. Baseline characteristics were not different in patients with and without serial CMR (data not shown).
There were 47 CTO LAD and 133 CTO non-LAD patients with serial CMR. Baseline and angiographic characteristics were comparable. However, we found remarkable differences in baseline LV function. In the LAD CTO subgroup, baseline LV function was significantly better in the CTO PCI arm compared with the no-CTO PCI arm. In the CTO non-LAD subgroup, baseline LV function was worse in the CTO PCI arm. Furthermore, in patients randomized to CTO PCI, success rates differed: 80.1% (LAD) and 71.2% (non-LAD) (p = 0.27).
In patients with serial CMR there was no effect of CTO PCI compared to no-CTO PCI on recovery of LV function (Figure 1). In CTO LAD at 4 months, LV ejection fraction (LVEF) increased, with 3.9 ± 9.2% in patients undergoing CTO PCI versus 3.8 ± 7.3% in the no-CTO PCI group (p = 0.97), and for LV end-diastolic volume (LVEDV) 6.3 ± 23.6 ml versus –4.0 ± 29.6 ml (p = 0.19), respectively. In CTO non-LAD patients there was also no effect of CTO PCI compared to no-CTO PCI on LV function (ΔLVEF: 5.0 ± 7.9% vs. 3.8 ± 7.3%, p = 0.44; ΔLVEDV: 5.1 ± 35.9 ml vs. 5.0 ± 24.3 ml, p = 0.98). Furthermore, there was no significant difference in recovery of LV function when comparing successful versus failed CTO PCI (ΔLVEF: 4.7 ± 8.1% vs. 4.4 ± 9.2%, p = 0.91; ΔLVEDV: 8.5 ± 28.0 ml vs. –5.8 ± 44.5 ml, p = 0.11).
In our main publication we report a significant interaction in the CTO LAD group in favor of CTO PCI on LV function. This has been taken up into the community to more liberally target CTO of LAD in post-STEMI patients. However, in patients with serial CMR, no significant difference in LV functional recovery was seen comparing CTO PCI versus no-CTO PCI.
The discrepancy in success percentage of CTO PCI across the CTO location may be influenced by differences in clinical and angiographic characteristics of CTO lesions (2). In elective CTO patients survival benefit of successful versus failed CTO PCI varied with the CTO location (3). Still, other aspects may influence the effect of CTO PCI: in our unique population with a STEMI and a CTO component, LV recovery might have been delayed and incomplete at 4-month follow-up. Furthermore, in an EXPLORE trial CMR substudy, a greater recovery of segmental wall thickening was seen after CTO PCI compared to no-CTO PCI, especially in dysfunctional segments in the CTO territory (4). Unfortunately, we did not perform routine viability testing of the CTO territory. However, >75% transmurality of myocardial infarction in the CTO territory was present in none of the patients. Future studies are needed to evaluate the effect of CTO PCI in more selected patients with longer follow-up.
Our study is limited by small sample sizes, lower than expected success rates of CTO PCI, and the EXPLORE trial was not powered for recovery of LV function. Inclusion of the EXPLORE trial took over 7 years and shock patients and patients with severely reduced LVEF were mostly excluded. Furthermore, baseline LVEF was significantly different in the subgroups. All of these factors might have influenced the results.
In conclusion, the previous beneficial finding of CTO PCI in CTO LAD patients was not supported in serial CMR data. Therefore, the short-term results of the EXPLORE trial do not support a strategy of routine early CTO PCI in STEMI patients, regardless of CTO location. However, the effect of CTO PCI in more selected patients at a longer follow-up needs further evaluation.
Please note: Dr. Henriques has received grant support from Abbott Vascular, BBraun, Abiomed, and Biotronik. All other authors have reported that they have no relationships relevant to the contents of this paper to disclose. Drs. Elias and Hoebers contributed equally to this work.
- 2017 American College of Cardiology Foundation
- Henriques J.P.,
- Hoebers L.P.,
- Ramunddal T.,
- et al.
- Hasegawa T.,
- Godino C.,
- Basavarajaiah S.,
- et al.
- Safley D.M.,
- House J.A.,
- Marso S.P.,
- Grantham J.A.,
- Rutherford B.D.
- ↵Henriques J. EXPLORE: Left ventricular function recovery from a prospective, randomized trial of CTO intervention after primary PCI in patients with STEMI. Paper presented at: Transcatheter Cardiovascular Therapeutics; October 31, 2016; Washington, DC.