In the US, there are about 200,000 recurring episodes and 550,000 first bouts of acute myocardial infarction every year. Acute myocardial infarction (AMI), which is typically brought on by an acute thrombotic occlusion of the coronary arteries, is still the world's most common cause of morbidity and mortality.1,2 Chronic total occlusion (CTO) of an artery is a near-total blockage of a coronary artery, evolving over 3 months,3 and is often seen during percutaneous coronary intervention (PCI) for cases of acute coronary syndrome in arteries not directly responsible for the event, known as non-infarct-related arteries (NIRA).

Cardiogenic shock (CS) is often a complication of AMI with significant morbidity and mortality.4 A variety of factors are commonly associated with the development of shock, including age, previous history of myocardial infarction (MI), presence of comorbidities, and STEMI.5 In patients with AMI-CS, angiography shows multivessel disease, with around a quarter of CTOs.4

With CTO in a NIRA in multi-vessel coronary disease, there is a higher association of mortality; CTO in an NIRA would cause the infarct-related artery to supply blood through its collaterals to the distal portions of the NIRA bed; hence, in case of an acute MI, the insufficient supply of blood to the heart tissue through collateral vessels would lead to a more extensive area of damage,4 and hence, arrhythmias, decreased left ventricular ejection fraction, and subsequently cardiogenic shock and death.5 In fact, such a finding in the context of MI complicated by CS has been found to be associated with mortality at 30 days5 and at 1 year.6

Interestingly, treatment of NIRA at the time of PCI for STEMI is not recommended because of increased morbidity and no additional survival benefit, especially in patients with hemodynamic stability.5 However, the impact of PCI in patients with CTO and CS should be investigated in future studies.

Our current systematic review and meta-analysis aimed to find an association between short- and long-term mortality along with an increased risk of repeat MI in patients undergoing PCI for STEMI and who have superimposed CS at admission, with the presence of CTO in a non-culprit artery.