Dr Gabriel Steg (Hopital Bichat-Claude Bernard, Paris) said the GRACE registry had found a higher rate of late mortality in ST elevated MI (STEMI) patients with DES thanwith bare metal stents (BMS). However, Steg conceded that this finding is in direct contrast to the SCAAR registry, which found no differences in survival between DES and BMS in the STEMI subset. These data were not disclosed in the SCAAR presentation in Monday’s ClinicalTrial Update Session.
Commenting on the GRACE findings, Steg said: “DES should be used cautiously in STEMI patients until there is further safety evidence from longterm trials. It will also be important to see how registry results pan out at three years.” He accepted that there was potential for a confounding bias in such observational registries.
Late stent thrombosis, although a rare event affecting less than 1% of DES patients, is a medical emergency, with patients dying in up to 45% of cases. There have been suggestions that the risk of late stent thrombosis is even greater in the context of acute coronary syndrome, particularly AMI, but only four randomised trials have been published in this area (TYPHOON, PASSION, SESAMI and STRATEGY) involving fewer than 900 patients.
GRACE is an ongoing observational registry of ACS. The analysis of late outcomes following PCI has so far gathered data on 6600 patients from 94 hospitals in 14 countries and is comparing the survival advantages of DES with BMS. This current sub-set analysis looked at STEMI patients only - 569 who had received DES and 1729 BMS.
Survival between six months and two years shows a statistically significant difference - 8.6% of patients receiving DES had died and 1.6% receiving BMS (p=0.001). This survival difference persisted after multiple logistic regression analysis.
“In the acute situation where there is a large thrombus and vasoconstriction, it’s particularly difficult to gauge the correct size of the stent,” said Steg. “With BMS this isn’t an issue, since re-endothelisation occurs within the next weeks or months, but in DES the gap may persist and can lead to malapposition of the stent, a factor predisposing to late stent thrombosis.”
The GRACE registry contained no information regarding the type of DES or BMS stent used, nor information on the characteristics of angiographic lesions treated, such as length and presence of calcification and bifurcation.
“There is now a need for a large prospective randomised trial with long-term follow-up,” said Steg, adding that there are hopes that newer DES devices producing more endothelization might present fewer problems.
The largest series of patients with stent thrombosis ever collected shows that 3.6% of emergency PCIs performed in acute MI are for stent thrombosis. The OPTIMIST study, involving 11 Rome hospitals, reviewed the clinical outcomes of 110 patients admitted with stent thrombosis; it showed that DES compared to BMS thrombosis happened more often after 30 days of implantation or 15 days of antiplatelet drug therapy withdrawal.
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'No need for confusion’
Session discussant William Wijns (Aalst, BE) said that the reassuring data from the SCAAR Swedish registry - and the fact that the GRACE registry showed no evidence of increased mortality of DES in non-STEMI at any time - represented good news. “The conflicting data from GRACE and SCAAR should not confuse,” he said, “since the strongest determinant of clinical outcomes is the case mix of patients getting the stent, which is decided by individual investigators.”