Relation of time to treatment on relative effects of primary coronary
angioplasty vs thrombolytic therapy A Patel*, F Zijlstra, M
Jones, C Grines, E Garcia, L Grinfeld, R Gibbons, E Ribeiro, F Ribichini, S
Ellis, C Granger, F Akhras, WD Weaver, RJ Simes, for the PCAT Collaboration NHMRC Clinical Trials
Centre, University of Sydney, Sydney We assessed the effect of
thrombolytic therapy (TT) vs primary coronary angioplasty (PTCA) on 30-day
mortality and reinfarction in 2635 patients with acute myocardial infarction
(MI), in an overview of individual patient data from 11 randomised trials. We
examined whether the relative effectiveness of these strategies was associated
with the time from the onset of symptoms to randomisation and with the time
from randomisation to treatment. Overall, PTCA was associated with a lower risk
of death at 30 days (odds ratio 0.62, 95% CI 0.44 to 0.86, p=0.004) or death
plus nonfatal MI (odds ratio 0.52, 95% CI 0.40 to 0.67, p<0.0001), with a
benefit observed to 6 months. For patients presenting later, with a longer time
from symptom onset to randomisation, there was a higher risk of death at 30
days and a trend to an even greater relative reduction in mortality for PTCA
compared with TT. In general, PTCA was started later than TT by 47 minutes
(median time from randomisation 69 minutes vs 22 minutes). A randomised
comparison of treatment within centres ranked by time to treatment showed a
trend towards a smaller relative treatment effect of PTCA at 30 days in centres
with a longer time difference between PTCA and TT. (P=0.06, see table). Centres
grouped by difference in time to Rx † n 30-day
death + MI (%) Odds
ratio (95% CI) PTCA TT <35
minutes 4.7 15.8 0.26
(0.15 - 0.46) 35-55
minutes 1152 7.9 12.5 0.60
(0.41 - 0.89) >55
minutes 8.3 12.1 0.66
(0.41 - 1.08) † Difference in
time from randomisation to initiation of treatment: PTCA vs TT Conclusions:
There is clear evidence of benefit of PTCA over TT in the treatment of
acute MI. However, the longer time to
initiate PTCA compared with TT may offset some of the advantage of PTCA and
needs to be taken into account when the results of these randomised trials are
applied to a broader community setting.
