IDEAL-LM: A randomized trial of a bioabsorbable polymer DES with 4-month DAPT vs. a durable polymer DES with 12-month DAPT in patients with left main coronary artery disease
Reported from the TCT Congress 2019 in San Francisco - USA
At TCT 2019 in San Francisco - USA, Robert-Jan Van Geuns presented the results of the IDEAL-LM trial. Read the analysis by Christopher Cook.
The methodology
Following the EXCEL and NOBLE trials, PCI for LMS disease continues to grow worldwide. However, the optimal duration of post-procedural DAPT in this important patient group is not clear. Given the large amount of myocardium at risk, some advocate a longer-term DAPT following LMS PCI. Conversely, others argue that the large vessel diameter and high flow conditions in the LMS might favour a shorter-term post PCI DAPT duration.
To help provide insight, IDEAL-LM randomised 818 all-comer LMS PCI patients to either the Synergy stent combined with 4 months of DAPT or to the Xience stent with 12 months of DAPT. The primary endpoint was the race of MACE (death, MI or ischaemia-driven TVR) at 2 years. Secondary endpoints (including major bleeding) were prespecified. A non-inferiority study design was adopted with a non-inferiority margin of 7.5%. The predicted MACE rate was estimated at 20% at 2 years.
What were the results?
The primary endpoint at 2 years occurred in 14.6% of patients treated with DAPT for 4 months following implantation with Synergy and 11.4% of patients treated with DAPT for 12 months following implantation with Xience (P = 0.17). Although statistically non-inferior, the upper limit of the 95% confidence interval of the absolute risk difference (7.18%) lay very close to the non-inferiority margin of 7.5%. Furthermore, the Xience and 12-month DAPT group fared numerically better across the majority of secondary endpoints. Paradoxically, this also included a statistically significantly lower rate of bleeding in the Xience and 12-month DAPT group as compared to the Synergy and 4-month DAPT group (0.5% vs 2.7%, p=0.02).
My take on this study
Overall, this study is continued good news for LMS PCI. The main clinical take home is the low event rate in this all-comer LMS PCI population at 2 years (much lower than the study investigators originally envisaged). However, some difficulties remain with translating the trial findings into routine clinical practice.
Firstly, the 7.5% non-inferior margin may be questioned by those who do not feel comfortable with the 3.8% absolute risk difference that was demonstrated between the two groups. Secondly, the all-comer population included those with ACS (~40%), in whom DAPT would conventionally always be continued longer than 4 months. Thirdly, although the all-comer design is good for generalisability, perhaps in LM patients where specific guidance on DAPT duration is needed, more targeted patient inclusion criteria may be needed to enhance the clarity of the study findings. Lastly, it is hard to tease out what role the DAPT duration played between the two groups when the stent platform itself also differed.
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