PLATO (NCT00391872) was a randomized double-blind study comparing ticagrelor tablets (N = 9333) to clopidogrel (N = 9291), both given in combination with aspirin and other standard therapy, in patients with acute coronary syndromes (ACS), who presented within 24 hours of onset of the most recent episode of chest pain or symptoms. The study’s primary endpoint was the composite of first occurrence of cardiovascular death, non-fatal MI (excluding silent MI), or non-fatal stroke.
Patients who had already been treated with clopidogrel could be enrolled and randomized to either study treatment. Patients with previous intracranial hemorrhage, gastrointestinal bleeding within the past 6 months, or with known bleeding diathesis or coagulation disorder were excluded. Patients taking anticoagulants were excluded from participating and patients who developed an indication for anticoagulation during the trial were discontinued from study drug. Patients could be included whether there was intent to manage the ACS medically or invasively, but patient randomization was not stratified by this intent.
All patients randomized to ticagrelor tablets received a loading dose of 180 mg followed by a maintenance dose of 90 mg twice daily. Patients in the clopidogrel arm were treated with an initial loading dose of clopidogrel 300 mg, if clopidogrel therapy had not already been given. Patients undergoing PCI could receive an additional 300 mg of clopidogrel at investigator discretion. A daily maintenance dose of aspirin 75-100 mg was recommended, but higher maintenance doses of aspirin were allowed according to local judgment. Patients were treated for at least 6 months and for up to 12 months.
PLATO patients were predominantly male (72%) and Caucasian (92%). About 43% of patients were > 65 years and 15% were > 75 years. Median exposure to study drug was 276 days. About half of the patients received pre-study clopidogrel and about 99% of the patients received aspirin at some time during PLATO. About 35% of patients were receiving a statin at baseline and 93% received a statin sometime during PLATO.
Table 7 shows the study results for the primary composite endpoint and the contribution of each component to the primary endpoint. Separate secondary endpoint analyses are shown for the overall occurrence of CV death, MI, and stroke and overall mortality.
Table 7: Patients with outcome events (PLATO) | Ticagrelor TabletsDosed at 90 mg bid. N = 9333 | Clopidogrel N = 9291 | Hazard Ratio (95% CI) | p-value |
Events / 1000 patient years | Events / 1000 patient years |
Composite of CV death, MI, or stroke | 111 | 131 | 0.84 (0.77, 0.92) | 0.0003 |
CV death | 32 | 43 | 0.74 | |
Non-fatal MI | 64 | 76 | 0.84 | |
Non-fatal stroke | 15 | 12 | 1.24 | |
Secondary endpoints Note: rates of first events for the components CV Death, MI and Stroke are the actual rates for first events for each component and do not add up to the overall rate of events in the composite endpoint. | | | | |
CV death | 45 | 57 | 0.79 (0.69, 0.91) | 0.0013 |
MI Including patients who could have had other non-fatal events or died. | 65 | 76 | 0.84 (0.75, 0.95) | 0.0045 |
Stroke | 16 | 14 | 1.17 (0.91, 1.52) | 0.22 |
All-cause mortality | 51 | 65 | 0.78 (0.69, 0.89) | 0.0003 |
The Kaplan-Meier curve (Figure 10) shows time to first occurrence of the primary composite endpoint of CV death, non-fatal MI or non-fatal stroke in the overall study.
Figure 10: Time To First Occurrence Of Cv Death, Mi, Or Stroke (plato) (Export 09)
Figure 10: Time to first occurrence of CV death, MI, or stroke (PLATO)The curves separate by 30 days [relative risk reduction (RRR) 12%] and continue to diverge throughout the 12-month treatment period (RRR 16%).
Among 11,289 patients with PCI receiving any stent during PLATO, there was a lower risk of stent thrombosis (1.3% for adjudicated “definite”) than with clopidogrel (1.9%) (HR 0.67, 95% CI 0.50-0.91; p = 0.009). The results were similar for drug-eluting and bare metal stents.
A wide range of demographic, concurrent baseline medications, and other treatment differences were examined for their influence on outcome. Some of these are shown in Figure 11. Such analyses must be interpreted cautiously, as differences can reflect the play of chance among a large number of analyses. Most of the analyses show effects consistent with the overall results, but there are two exceptions: a finding of heterogeneity by region and a strong influence of the maintenance dose of aspirin. These are considered further below.
Most of the characteristics shown are baseline characteristics, but some reflect post-randomization determinations (e.g., aspirin maintenance dose, use of PCI).
Figure 11: Subgroup Analyses Of (plato) (Export 08)
Figure 11: Subgroup analyses of (PLATO)Note: The figure above presents effects in various subgroups most of which are baseline characteristics and most of which were pre-specified. The 95% confidence limits that are shown do not take into account how many comparisons were made, nor do they reflect the effect of a particular factor after adjustment for all other factors. Apparent homogeneity or heterogeneity among groups should not be over-interpreted.