Abstract: We included nine RCTs, that involved 2633 people with STEMI and multi-vessel coronary disease randomly assigned to either a complete (n = 1381) versus culprit-only (n = 1252) revascularisation strategy. The complete and the culprit-only revascularisation strategies did not differ for long-term all-cause mortality (65/1274 (5.1%) in complete group versus 72/1143 (6.3%) in culprit-only group; RR 0.80, 95% CI 0.58 to 1.11; participants = 2417; studies = 8; I2 = 0%; very low quality evidence). Compared with culprit-only intervention, the complete revascularisation strategy was associated with a lower proportion of long-term cardiovascular mortality (28/1143 (2.4%) in complete group versus 51/1086 (4.7%) in culprit-only group; RR 0.50, 95% CI 0.32 to 0.79; participants = 2229; studies = 6; I2 = 0%; very low quality evidence) and long-term non-fatal myocardial infarction (47/1095 (4.3%) in complete group versus 70/1004 (7.0%) in culprit-only group; RR 0.62, 95% CI 0.44 to 0.89; participants = 2099; studies = 6; I2 = 0%; very low quality evidence). The complete and the culprit-only revascularisation strategies did not differ in combined adverse events (51/2096 (2.4%) in complete group versus 57/1990 (2.9%) in culprit-only group; RR 0.84, 95% CI 0.58 to 1.21; participants = 4086; I2 = 0%; very low quality evidence). Complete revascularisation was associated with lower proportion of long-term revascularisation (145/1374 (10.6%) in complete group versus 258/1242 (20.8%) in culprit-only group; RR 0.47, 95% CI 0.39 to 0.57; participants = 2616; studies = 9; I2 = 31%; very low quality evidence). TSA of long-term all-cause mortality, long-term cardiovascular mortality, and long-term non-fatal myocardial infarction showed that more RCTs are needed to reach more conclusive results on these outcomes. Regarding long-term repeat revascularisation more RCTs may not change our present result. The quality of the evidence was judged to be very low for all primary and the majority of the secondary outcomes mainly due to risk of bias, imprecision, and indirectness. Compared with culprit-only intervention, the complete revascularisation strategy may be superior due to lower proportions of long-term cardiovascular mortality, long-term revascularisation, and long-term non-fatal myocardial infarction, but these findings are based on evidence of very low quality. TSA also supports the need for more RCTs in order to draw stronger conclusions regarding the effects of complete revascularisation on long-term all-cause mortality, long-term cardiovascular mortality, and long-term non-fatal myocardial infarction.

Plain-language summary: We searched for clinical trials in adults who had percutaneous coronary intervention for the management of heart attack and multi-vessel disease. The evidence is current to 4 January 2017. Only four trials reported funding from government organisations or charitable institutions. The other trials did not mention the source of funding and no private companies were mentioned as sources of finance. In the included trials, both the participants and researchers were aware of what treatment the participants received which may have biased the results. One trial ended enrolment earlier than planned because the difference between treatment was significant. This may have overestimated the difference between intervention groups. For most trials, the number of participants that were included was not enough to see a potential difference between treatments. We included nine clinical trials with 2633 people with heart attack and multi-vessel disease. Compared with participants who underwent opening of only the coronary artery that caused heart attack, people who underwent treatment on all narrowed vessels had fewer deaths from diseases of the heart and blood supply (called cardiovascular disease), required fewer treatments to open the problematic coronary arteries, and had fewer heart attacks at the end of one year or later since the treatment. Based on our analyses, although the treatment on all narrowed vessels appears to be a better treatment strategy, there still exists a need for more well-designed clinical trials to confirm that this approach is associated with fewer deaths from cardiovascular diseases or heart attack, or both. The evidence is of very low quality. For instance, the number of participants in the included studies was insufficient, the medical team was aware of the study group that the participants were allocated to and that may have affected our conclusions. There is a need for well-designed clinical trials with more participants to determine which treatment strategy is superior.