We read with interest the recent report by Cavender et al, questioning the guidelines and use of multivessel percutaneous coronary intervention (PCI) in the setting of ST elevation myocardial infarction (STEMI). The investigators concluded that multivessel primary PCI for STEMI does not improve in-hospital outcomes, even in patients with cardiogenic shock.

We recently investigated the impact of multivessel disease (MVD) with or without a chronic total occlusion (CTO) in a non-infarct-related artery. From 1997 to 2005, we treated 3,277 patients with STEMIs with primary PCI at our center. Patients were categorized as having single-vessel disease, MVD without a CTO, or MVD with a CTO in a non-infarct-related artery. We performed a “landmark survival analysis” to 5-year follow-up, with a landmark set at 30 days. A CTO in a non-infarct-related artery was a strong and independent predictor of 30-day mortality (adjusted hazard ratio 3.6, p <0.01), whereas MVD without a CTO was only a weak predictor (adjusted hazard ratio 1.6, p <0.01). In 30-day survivors, a CTO in a non-infarct-related artery remained a strong predictor (adjusted hazard ratio 1.9, p <0.01), whereas MVD without a CTO lost its independent prognostic value. This was also true for a cohort of patients with cardiogenic shock only. Furthermore, a CTO in a non-infarct-related artery was associated with worse left ventricular function during hospitalization for the index event and a decrease in left ventricular function during follow-up. Patients with MVD without CTOs had left ventricular function comparable to that of patients with single-vessel disease.

In addition to the possible mechanisms by which revascularization of the non-infarct-related artery is associated with increased mortality mentioned by Cavender et al, our data suggest another possible mechanism. Because the presence of a total occlusion rather than a stenosis in a non-infarct-related artery seems to drive the worse prognosis in patients with STEMIs with MVD, it is questionable if the treatment of additional nonculprit lesions (with the exception of CTOs) will result in any clinical benefit.

Therefore, we recently initiated the Evaluating Xience V and Left Ventricular Function in PCI on Occlusions After STEMI (EXPLORE) trial, the first randomized clinical trial powered to investigate clinical outcomes after the percutaneous treatment of CTOs. EXPLORE is a multicenter randomized clinical trial in which 300 patients with STEMIs treated with primary PCI with CTOs in non-infarct-related arteries will be randomized to either PCI of the CTO in a staged procedure <7 days after the index event or standard medical post-STEMI treatment. The EXPLORE trial will determine whether additional percutaneous treatment of a CTO after STEMI improves the left ventricular ejection fraction and reduces left ventricular end-diastolic volume measured by cardiac magnetic resonance imaging at 4-month follow-up.