No Reflow in Acute Coronary Syndromes: An Old Foe or a New Frontier?

According to the World Health Organization (WHO), ischemic heart disease is the leading cause of death worldwide, accounting for 16% of the world’s deaths in 2019. However, due to continuous evolution in medical treatment and revascularization techniques, a steady decline in death rates in acute coronary syndromes (ACS) has been observed in recent years.

Currently, percutaneous coronary intervention (PCI) is the gold-standard treatment for ST-elevation myocardial infarction (STEMI) and a mainstay therapeutic option for non-STEMI ACS and stable coronary artery disease. Nonetheless, and particularly in STEMI patients, PCI can be very challenging at times. One of the most dreaded events during PCI in STEMI is the phenomenon commonly referred as “no-reflow”, an impaired myocardial perfusion secondary to microvascular obstruction without angiographic evidence of coronary obstruction(6). Initially described in animal models,^, it was also recognized in humans in the following decades,^, being first described after PCI for STEMI by Feld in 1992. Its occurrence is related to poorer short- and long-term outcomes following PCI,^, and it is present in more than 20% of patients undergoing primary PCI for STEMI.

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