The DAPT Trial – Turning What We Thought We Knew on its Head
In the DAPT study 229,661 patients with a mix of elective and ACS presentations, who had undergone PCI using DES 1 and DES 2 and who had had an uneventful period of DAPT treatment for 12 months already, were then randomised to either a further 18 months of DAPT or aspirin plus placebo. There was a significant reduction in both ST (p<0.001), a specified co-primary endpoint and major adverse CV and cerebrovascular events (p<0.001) in the prolonged duration DAPT group compared with aspirin monotherapy. However, there was a significant increase in important bleeding in the 30-month DAPT group (p=0.001). Another interesting observation was that although all- cause mortality was no different between the groups, the prolonged DAPT group had a significantly higher rate of non-cardiovascular death (p=0.002).
The DAPT trial investigators concluded that the prolonged DAPT regimen (30 months) reduced ischaemic events, including ST, compared with 12 months’ DAPT. The implications of this trial are not yet as clear as they first seem. There is concern about committing all DES patients to a longer regimen associated with more severe bleeding. But also, despite the temptation to put the increased incidence of non-cardiovascular death down to statistical quirk, this raises alarm bells given the large number of patients worldwide being treated in this way. The meta-analysis by Palmerini et al., which includes the DAPT trial, just published in The Lancet,23 confirms that we should indeed take a cautious approach to a universal switch to prolonged DAPT after DES. The analysis includes more than 32,000 patients and confirms that there is a 33 % lower rate of non-cardiovascular mortality in the shorter duration DAPT arm compared with longer duration, and this actually drives a hazard ratio of 0.82 for all-cause mortality in the shorter duration group. On the other side of the coin, a meta-analysis by Elmariah et al., which involved 14 studies including the DAPT study, showed that extended-duration was not associated with a difference in the risk of all-cause, cardiovascular or non- cardiovascular death compared with aspirin alone or short-duration.24