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TENACITY was a randomized 2 × 2 factorial trial comparing high-dose bolus (HDB) tirofiban vs. abciximab, and unfractionated heparin (UFH) vs. bivalirudin, in patients undergoing percutaneous coronary intervention (PCI). The primary endpoint of 30-day death, myocardial infarction, or urgent target vessel revascularization occurred in 6.9% and 8.8% of patients randomized to HDB tirofiban and abciximab, respectively. In this analysis, we retrospectively analyzed CK-MB levels in the 4 arms of the study.
Serial CK-MB samples were obtained in 380 of the 383 enrolled patients.
A non-inferiority analysis with margin of 2 ng/mL was performed using PROC TTEST of SAS version 9.2, with HDB tirofiban and abciximab study arms pooled across levels of UFH and bivalirudin. The non-inferiority of HDB tirofiban vs. abciximab was established from a one-sided test for the difference in peak CK-MB means (p-value = 0.011), with a corresponding 90% confidence interval of (−0.52, 6.86) for abciximab minus HDB tirofiban.
|Variable Analyzed||HDB Tirofiban + AT (n=189) (ng/mL)||Abciximab + AT (n=191) (ng/mL)||UFH + GPI (n=195) (ng/mL)||Bivalirudin + GPI (n=185) (ng/mL)|
|Median Peak CK-MB||2.6||2.6||2.7||2.5|
|Peak CK-MB Percentile 25-75||1.6-6.4||1.3-5.5||1.3-6.4||1.4-5.6|
|Median CK-MB from serial draw #1||1.5||1.5||1.6||1.4|
|Median CK-MB from serial draw #2||1.8||1.8||1.8||1.8|
|Median CK-MB from serial draw #3||2.1||2.2||2.2||2.1|
|Median CK-MB from serial draw #4||2.2||2.3||2.3||2.3|
|Median CK-MB from serial draw #5||2.5||3.1||3.5||2.3|
AT=UFH or bivalirudin; GPI=tirofiban or abciximab.
CK-MB levels are similar after the administration of HDB tirofiban and abciximab, and UFH and bivalirudin, in this prematurely terminated, undersized trial. These data do suggest, however, that HDB tirofiban and abciximab, and UFH and bivalirudin, may be similar in their ability to prevent peri-procedural myocardial infarction in moderate to high-risk patients undergoing PCI. These data should be useful in identifying the size of an appropriately powered trial necessary to compare these regimens.
- 2013 American College of Cardiology Foundation