Early invasive versus ischaemia-guided strategies in the management of non-Q wave myocardial infarction patients with and without prior myocardial infarction; results of Veterans Affairs Non-Q Wave Infarction Strategies in Hospital (VANQWISH) trial

Abstract

Aims: To compare the role of early invasive vs conservative management strategies in treating patients with non-Q wave myocardial infarction with or without a prior myocardial infarction.

Background: In patients recovering from non-Q wave myocardial infarction, the prognosis among patients with a first non-Q wave myocardial infarction is significantly better than in patients with a prior myocardial infarction, yet physicians often adopt an early invasive strategy to treat patients with a first non-Q wave myocardial infarction.

Methods: Non-Q wave myocardial infarction patients enrolled in the VANQWISH trial with a history of prior myocardial infarction were compared to those with a first non-Q wave myocardial infarction, for the trial primary end-point of death or myocardial infarction at 1 and 12 months, as well as for the initial randomized treatment strategy.

Results: Of the 920 non-Q wave myocardial infarction patients, 396 had a history of prior myocardial infarction and 524 did not. Patients with a history of prior myocardial infarction were older and had a higher incidence of multiple high-risk baseline characteristics than those with a first non-Q wave myocardial infarction. Compared to the group with a first myocardial infarction, the prior myocardial infarction group suffered more events at both 1 month (11% vs 6%, P=0.007) and at 12 months (29% vs 16%, P<0.001). This difference in outcome remained significant even after adjusting for confounding variables (P<0.0001 at 12 months). Among the non-Q wave myocardial infarction patients with a prior myocardial infarction, the frequency of death or recurrent myocardial infarction was similar in both invasive and conservative groups during the first year of follow-up. Among the first non-Q wave myocardial infarction group, those assigned to the conservative strategy had significantly fewer events (3% vs 9%, P=0.009 at 1 month; 12% vs 20%, P=0.016 at 12 months) and mortality (1% vs 5%, P=0.012 at one month; 5% vs 11%, P=0.009 at 12 months) than those assigned to early invasive strategy.

Conclusion: A history of prior myocardial infarction identifies a moderately high-risk subset of non-Q wave myocardial infarction patients who display similar long-term outcomes regardless of the strategy assignment; however, patients with a first non-Q wave myocardial infarction may fare better with a conservative or ischaemia-guided approach during the first post infarction year.