Multivessel disease (MVD) is found in 40–65% of patients with ST‐segment myocardial infarction (STEMI) undergoing primary percutaneous coronary intervention (PCI) and is associated with a worse prognosis.1,2

However, the latest European Society of Cardiology (ESC) guidelines on STEMI limit multivessel PCI to cases of cardiogenic shock and recommend ischemia testing before PCI of non‐culprit vessels,3 but the data to support this safety concern are scant and studies and meta‐analyses examining strategies for MVD in STEMI continue to give conflicting results.4,5

A staged revascularization approach, with initial PCI of the culprit artery and subsequent revascularization of non‐culprit vessels is associated with lower mortality in STEMI patients with MVD compared to primary PCI of the culprit vessel and all other arteries with significant lesions.6,7 On the other hand, a registry and meta‐analysis including 61 764 STEMI patients with MVD showed that a multivessel revascularization strategy at the time of culprit lesion PCI is safe and is associated with a reduced rate of revascularization.4

Given the lack of evidence for the optimal approach to primary PCI in MVD, the aim of this study was to assess the impact of a multivessel approach on in‐hospital morbidity and mortality in patients with STEMI undergoing primary PCI included in the Portuguese Society of Cardiology's Registry of Acute Coronary Syndromes (ACS).

We analyzed all patients with STEMI in the ACS Registry who underwent primary PCI between October 1, 2010 and October 31, 2011 (n=921) and who presented MVD, defined as ≥50% stenosis (n=399). Patients who underwent PCI of a non‐culprit vessel in a second procedure (n=132) were excluded, as were those with a history of coronary artery bypass surgery (n=10).

A total of 257 patients were included, who were divided into two groups: group 1, who underwent PCI of the culprit artery only (n=180) and group 2, those who underwent multivessel PCI (n=77). Demographic data, cardiovascular risk factors, STEMI location as defined in the ACS Registry (anterior myocardial infarction [MI], inferior MI, or MI with new‐onset left bundle branch block [LBBB]), systolic blood pressure and heart rate at admission, pain‐to‐balloon time, in‐hospital treatment, number and type of diseased and treated arteries, percentage of drug‐eluting stents, and ejection fraction were recorded.

The primary end‐point was defined as in‐hospital mortality and the secondary end‐point as the presence of at least one of the following complications: major bleeding as defined by the GUSTO criteria, need for transfusion, invasive ventilation, heart failure and reinfarction.

This study at the national level, which included various centers in Portugal, set out to analyze the impact of a multivessel approach in a real‐world population of STEMI patients undergoing PCI. The fact that the study population was taken from the ACS Registry, the inclusion criteria for which are clearly defined and applied equally to all centers, means that the same clinical data were available for all patients and could thus be analyzed in the same way.

MVD is common in STEMI patients undergoing primary PCI and is associated with higher morbidity and mortality. The prevalence of MVD in our study was 43.3%, a similar figure to that found in the EUROTRANSFER Registry and a South Korean registry, in which the prevalence was 51.5% and 47.9%, respectively.2,8

Despite the implications for prognosis, the ESC guidelines on STEMI and on myocardial revascularization continue to recommend multivessel PCI in STEMI only for patients with refractory heart failure and/or cardiogenic shock. However, in the real world, various registries show that a multivessel approach is adopted in between 9% and 24.4% of cases.2,4,9 In the Portuguese ACS Registry, this figure was 19.2%.

According to some authors, this discrepancy between the guidelines and clinical practice is the result of a lack of clinical evidence; the subject continues to arouse debate, which can only be resolved by a large international multicenter trial.

In our study, we set out to assess the impact of a multivessel approach on in‐hospital morbidity and mortality in patients with STEMI undergoing primary PCI.

The patients were divided into two groups: group 1, who underwent PCI of the culprit artery only and group 2, those who underwent multivessel PCI. The groups were similar in baseline clinical characteristics, with no significant differences in age, gender, cardiovascular risk factors or ECG presentation of MI (Table 1). The majority of patients in both groups were male, reflecting the higher prevalence of cardiovascular disease in men.

Hypertension was the most common cardiovascular risk factor, found in around 70% of patients, reflecting the high prevalence of hypertension in Portugal. Dyslipidemia was the second most frequent risk factor, while the percentages for smoking and diabetes were similar.

Angiography revealed that patients in group 1 had a slightly higher prevalence of 3‐vessel disease than in group 2 (31.8% vs. 27.3%; p<0.001). This may be explained by the fact that, although complete revascularization of 3‐vessel disease may improve prognosis, it is also associated with longer procedure times, increased contrast use, and greater risk of periprocedural MI.5 No significant differences in left main disease were found between the groups.

Pharmacological therapy (Table 2) followed the ESC guidelines for STEMI, with 100% of patients receiving aspirin and clopidogrel, around 95% receiving statins and around 80% receiving ACE inhibitors or angiotensin receptor blockers and beta‐blockers. Except for heparin (used more in group 1) and glycoprotein IIb/IIIa inhibitors (used more in group 2), there were no significant differences between the groups. The use of glycoprotein IIb/IIIa inhibitors in STEMI patients was the subject of a large meta‐analysis by de Luca et al., which concluded that the benefits were greater in higher‐risk patients.10 This may explain their higher rate of use in more complex procedures such as multivessel PCI.

Traditionally, drug‐eluting stents have been associated with lower restenosis and revascularization rates and improved survival in STEMI patients.11–14 This may explain why they were used more frequently in patients undergoing multivessel PCI than in those undergoing culprit artery PCI only, in whom bare‐metal stents were more common.

No significant differences were seen in our population in either the primary (in‐hospital mortality) or secondary (any of the defined complications) endpoints. However, those undergoing multivessel PCI had a higher prevalence of normal left ventricular function during hospitalization (62.7% vs. 44.7%; p=0.006). The significance of this finding is unclear, since the ACS Registry data do not specify whether patients’ ejection fraction was assessed before or immediately after PCI or before discharge.

The quest for the optimal strategy for MVD in STEMI patients remains the subject of debate.5 In a retrospective study, Hannan et al. compared mortality in‐hospital and at 12, 24, and 42 months in patients who underwent culprit vessel PCI only or multivessel PCI in the index procedure or subsequently, and concluded that culprit vessel PCI was associated with lower in‐hospital mortality and staged multivessel PCI was associated with lower 12‐month mortality.7 Similarly, a meta‐analysis of four prospective and 14 retrospective studies including a total of 40 280 patients concluded that a staged approach to MVD (primary PCI of the culprit vessel and PCI of non‐culprit vessels in subsequent procedures) was associated with lower mortality than primary PCI of the culprit vessel only and that simultaneous multivessel PCI resulted in the highest short‐ and long‐term mortality.6 The conclusions of both these studies support the recommendations in the ESC guidelines on STEMI and on myocardial revascularization.

On the other hand, the South Korean registry revealed no significant differences in mortality, MI or revascularization at one year between patients undergoing culprit vessel PCI only or multivessel PCI.8 Similar conclusions had previously been drawn in a small prospective trial by Khattab et al.,15 while a meta‐analysis by Bengalore et al. involving 61 764 patients found no significant differences in short‐term mortality, MI or stroke or in long‐term MI, stent thrombosis or target vessel revascularization, the authors concluding that multivessel PCI appears to be safe compared to culprit artery‐only revascularization.4

As in this meta‐analysis and the Korean registry, in our study there were no differences between the groups in mortality or the incidence of complications.

Since the existing studies and meta‐analyses on a multivessel approach to STEMI draw conflicting conclusions, there is a need for large randomized multicenter trials to clarify the question, for which our study may provide a further stimulus.

This study has the limitations inherent to all registry‐based analyses. The ACS Registry is voluntary, and so not all centers in Portugal participate and participating centers do not necessarily include all their patients; as a result the sample size is small, which reduces the statistical validity of some of the differences between the groups.

Another limitation derives from the format of the ACS Registry, in which the criteria used by different operators to decide between culprit vessel PCI only and multivessel PCI are not specified, which also weakens the validity of some of the results obtained.

In our population of STEMI patients undergoing primary PCI, the prevalence of MVD was 43.3%, and a simultaneous multivessel approach was adopted in 19.2%. A multivessel approach appears to be a safe alternative to conventional culprit‐vessel only PCI, with a non‐significant tendency for lower in‐hospital morbidity and mortality.

The authors have no conflicts of interest to declare.