CardioExchange Archive

CardioExchange, an NEJM practice community for medical professionals dedicated to improving cardiac patient care, was active from 2009 to 2015. CardioExchange fostered discussion between clinicians from across the globe.

January 9th, 2012

Do Drug-Eluting Stents Reduce Death? The Devil, the Details, and the Missing Swedes

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In a 2009 NEJM article, the Swedish Coronary Angiography and Angioplasty Registry (SCAAR) study group published 1 to 5 (mean, 2.7) year follow-up data for almost 48,000 registry patients who received a bare metal (BMS) or drug-eluting coronary stent (DES) between 2003 and 2006, concluding that the two are associated with a similar long-term incidence of death.

Now the same group reports in the European Heart Journal that DES reduce the incidence of death when compared to BMS.  Examining follow-up data from 94,384 consecutive stent implantations recorded in SCAAR from 2006 to 2010, they report that older generation DES (i.e., the same ones reported in the 2009 study) were associated with a significantly lower mortality (adjusted HR, 0.72; 95% CI, 0.64–0.81) when compared with BMS; furthermore, the risk of death in those receiving a newer DES was even lower than those receiving an older DES (adjusted HR, 0.77; 95% CI, 0.63–0.95).

Although the authors of the recent analysis warn that their results “need to be interpreted with caution” (because it is an observational study), they argue that the larger sample size of the more recent study may have provided “more statistical power to detect differences in low-frequency events, such as death.”

Wait just a moment….the devil is in the details of the study.  Of the 29,753 DES patients whose data comprise the recent study, follow-up information was available at 1 and 2 years in relatively few —  much fewer, in fact, than in the 2009 study.

 

No patients enrolled

No. at risk
at 1 yr

No. at risk
at 2 yrs
2009 study
 BMS

28,286

26,843

19,429
 DES

19,681

12,691

12,691
Recent study
BMS

64,631

31,329

21,813
Older DES

19,202

6857

4679
Newer DES

10,551

1636

346

 

One might legitimately inquire, “Where are the missing Swedes?” Of the 29,753 DES subjects whose data are reported in the recent study, 2-year follow-up data were available in only 5,025 (17%).  Even more striking, of the 10,551 DES patients, 2-year follow-up data were available in only 346 (3%!!).  I’d expect more to be alive and available for follow-up if DES actually reduces death.

Now which is correct, the 2009 study or the more recent study?  Is mortality truly lower with DES when compared to BMS?  

 

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