CTO PCI does not affect diastolic coupling in STEMI patients; elevated baseline LACI predicts mortalityDoes opening a blocked artery after a heart attack help the heart relax?

International journal of cardiology Published April 3, 2026 Study authors: Coerkamp Casper F, Hinderks Mark J, Elias Joëlle, van Veelen Anna, Hoebers Loes P C, Råmunddal Truls… PubMed ↗ DOI ↗ Editorial oversight: Dr. Amelia Tan, PhD · Internal Medicine & Chronic Disease

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Key Takeaway

Note: CTO PCI did not improve diastolic coupling; elevated baseline LACI associated with mortality risk.

This multicenter randomized controlled trial (EXPLORE trial) examined the effect of percutaneous coronary intervention (PCI) for chronic total occlusion (CTO) on diastolic atrioventricular coupling in 200 patients with ST-elevation myocardial infarction (STEMI) and concurrent CTO. Patients were randomized to CTO PCI or no-CTO PCI, with 178 patients completing cardiac MRI assessment at 4-month follow-up. The primary outcome was change in left atrioventricular coupling index (LACI), a measure of diastolic function.

CTO PCI did not significantly affect the change in LACI over 4 months (effect size -0.8%, P=0.122). LACI improved significantly over time in the overall cohort (Δ LACI -1.0%, P=0.005), but this improvement was not influenced by CTO revascularization. In an observational analysis within the trial, baseline LACI ≥20.6% was independently associated with increased risk of all-cause death during follow-up (hazard ratio 2.37, 95% CI: 1.27 to 4.45, P=0.007).

Safety and tolerability data were not reported. The study has limitations including the observational nature of the mortality analysis, which precludes causal inference about LACI and mortality. The 4-month follow-up may be insufficient to detect longer-term effects on diastolic function or clinical outcomes.

For practice, CTO PCI did not demonstrate benefit on diastolic atrioventricular coupling in this population. The association between elevated baseline LACI and mortality suggests this parameter may have prognostic value in STEMI patients with CTO, but this requires confirmation in prospective studies. Clinicians should interpret the mortality finding cautiously as it represents an association rather than a treatment effect.

When someone has a major heart attack, doctors rush to open the blocked artery causing it. But many patients also have a second, older artery that's been completely blocked for a long time—a 'chronic total occlusion.' The big question is whether opening that old blockage helps the heart recover. This trial looked at 200 patients who had both a fresh heart attack and one of these old blockages. Half had the old blockage opened with a stent, and half did not. The researchers used advanced heart scans to measure something called the left atrioventricular coupling index (LACI), which is a way to see how efficiently the heart's main pumping chamber relaxes and fills with blood. After four months, LACI improved slightly in all patients, but there was no meaningful difference between the group that had the extra procedure and the group that didn't. The procedure simply didn't move the needle on this measure of heart relaxation. Here's the twist the researchers found: patients who had a high LACI score right after their initial heart attack were more than twice as likely to die from any cause in the years that followed. This suggests that how well the heart relaxes early on is a powerful warning sign. It's crucial to note that this link is an observation from the study data, not proof that fixing the LACI would change survival. And since the procedure didn't improve LACI, it doesn't support using it for that purpose.

What this means for you:

Opening an old heart blockage didn't improve heart relaxation, but poor relaxation after a heart attack signals higher death risk.

Study Details

Study typeRct

Sample sizen = 200

EvidenceLevel 2

Follow-up4.0 mo

PublishedApr 2026

PMID41519388

View Original Abstract ↓

Percutaneous coronary intervention (PCI) for chronic total occlusion (CTO) did not improve left ventricular systolic function. The left atrioventricular coupling index (LACI), derived from cardiovascular magnetic resonance (CMR), reflects diastolic atrioventricular coupling and has recently emerged as a parameter for diastolic dysfunction and a prognostic marker after acute myocardial infarction. We aimed to assess the impact of CTO PCI on LACI in patients with ST-elevation myocardial infarction (STEMI) and concurrent CTO METHODS: In this CMR substudy of the multicentre randomised controlled EXPLORE trial, 200 patients (mean age 60 ± 10 years, 88% male) underwent baseline CMR, and 178 patients had analysable 4-month follow-up CMR. LACI was defined as the ratio of left atrial and left ventricular end-diastolic volumes. The primary outcome was the effect of CTO PCI on LACI and change of LACI over time RESULTS: The significant improvement in LACI over time (Δ LACI - 1.0% [Q1-Q3: - 4.6 to 2.0], P = 0.005) was independent of CTO PCI or no-CTO PCI (P = 0.706). CTO PCI did not influence the change in LACI (- 0.8% [Q1-Q3: - 4.7 to 2.2], P = 0.122). Baseline LACI ≥20.6% was associated with an increased risk of all-cause death compared to LACI <20.6% after multivariable adjustment (hazard ratio 2.37, 95% CI: 1.27 to 4.45, P = 0.007) CONCLUSIONS: Among STEMI patients with a concurrent CTO, CTO PCI did not affect LACI at 4 months or its improvement over time. Elevated LACI early after STEMI independently predicted long-term all-cause mortality Clinical trial registration: The Evaluating Xience and left ventricular function in PCI on occlusiOns afteR STEMI (EXPLORE) trial; NTR1108 www.trialregister.nl, Date registered NTR: 30-okt-2007.

CTO PCI does not affect diastolic coupling in STEMI patients; elevated baseline LACI predicts mortalityDoes opening a blocked artery after a heart attack help the heart relax?

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