Safety and efficacy of the 0 h/3 h protocol for rapid rule out of myocardial infarction

BACKGROUND: The early and accurate diagnosis of acute myocardial infarction (AMI) is an important medical and economic challenge. We aimed to prospectively evaluate the performance of the new European Society of Cardiology rapid 0-hour/3-hour (0 h/3 h) rule out protocol for AMI.

METHODS: We enrolled 2,727 consecutive patients presenting with suspected AMI without persistent ST-segment elevation to the emergency department in a prospective international multicenter study. The final diagnosis was adjudicated by 2 independent cardiologists. The performance of the 0 h/3 h rule out protocol was evaluated using 4 high-sensitivity (primary analysis) and 3 sensitive cardiac troponin (cTn) assays.

RESULTS: Acute myocardial infarction was the final diagnosis in 473 patients (17.3%). Using the 4 high-sensitivity cTn assays, the 0-hour rule out protocol correctly ruled out 99.8% (95% [confidence interval] CI, 98.7%-100%), 99.6% (95% CI, 98.5%-99.9%), 100% (95% CI, 97.9%-100%), and 100% (95% CI, 98.0%-100%) of late presenters (>6 h from chest pain onset). The 3-hour rule out protocol correctly ruled out 99.9% (95% CI, 99.1%-100%), 99.5% (95% CI, 98.3%-99.9%), 100% (95% CI, 98.1%-100%), and 100% (95% CI, 98.2%-100%) of early presenters (<6 h from chest pain onset). Using the 3 sensitive cTn assays, the 0-hour rule out protocol correctly ruled out 99.6% (95% CI, 98.6%-99.9%), 99.0% (95% CI, 96.9%-99.7%), and 99.1% (95% CI, 97.2%-99.8%) of late presenters; and the 3-hour rule out protocol correctly ruled out 99.4% (95% CI, 98.3%-99.8%), 99.2% (95% CI, 97.3%-99.8%), and 99.0% (95% CI, 97.2%-99.7%) of early presenters. Overall, the 0 h/3 h rule out protocol assigned 40% to 60% of patients to rule out. None of the patients assigned rule out died during 3-months follow-up.

CONCLUSIONS: The 0 h/3 h rule out protocol seems to allow the accurate rule out of AMI using both high-sensitivity and sensitive cTn measurements in conjunction with clinical assessment. Additional studies are warranted for external validation.