Circadian dependence of manual thrombus aspiration benefit in patients with ST-segment elevation myocardial infarction undergoing primary percutaneous coronary intervention

Background: The clinical benefit of manual thrombus aspiration (TA) during primary percutaneous coronary intervention (PPCI) in patients with ST-segment elevation myocardial infarction (STEMI) remains uncertain. This study assessed the impact of circadian rhythms on the effectiveness of manual TA. Methods and results: We conducted an observational study of patients enrolled in the Acute Myocardial Infarction in Switzerland Plus registry. STEMI patients undergoing PPCI with (TA group) or without (PCI-alone group) manual TA were divided based on time-of-day symptom onset: group 1 (00:00–05:59), group 2 (06:00–11:59), group 3 (12:00–17:59) and group 4 (18:00–23:59). The primary endpoint was circadian variation of myocardial infarction (MI) size. The secondary endpoint was in-hospital all-cause mortality. Between 2009 and 2014, 3648 patients underwent PPCI (TA, 49%). After propensity-score matching, 2860 patients were included. Minimal myocardial Injury was observed in groups 2 and 3 (peak creatine kinase level group 1, 2723 ± 148 U/l; group 2, 2493 ± 105 U/l; group 3, 2550 ± 106 U/l; group 4, 2952 ± 144 U/l; p = 0.044) in the TA group, whereas no time-of-day dependence was found in PCI-alone group. After periodic sinusoidal regression analysis, a circadian relationship between time-of-day symptom onset and MI size was demonstrated in the TA group (p < 0.001). In-hospital all-cause mortality was 3.4% in the TA group and 4.3% in the PCI-alone group (p = 0.20). Conclusions: In this large registry of STEMI patients, manual TA did not reduce in-hospital all-cause mortality. Nonetheless, there was a circadian dependence of TA effectiveness with greatest myocardial salvage for patients with symptom onset between 06:00 and 17:59.