INTRODUCTION
Ventricular septal rupture (VSR) is a rare but fatal mechanical complication of acute myocardial infarction (AMI), with associated medical management mortality that ranges from 41% to 80% 1-4.  Traditional opinion believed immediate repair for VSR was necessary because rupture can expand abruptly, resulting in sudden hemodynamic collapse. The 2013 AHA guidelines for STEMI concluded that emergency surgical repair is recommended for all patients with VSR, even in hemodynamically stable patients5. Although surgery is recognized as the most effective treatment for VSR, it carries an exceedingly high postoperative mortality of 42.9~80.5% within 7 days of VSR onset2,6.
However, due to an unperfect transportation system in middle-income economies like China, a large proportion of VSR patients were not able to receive emergency transportation to qualified cardiac surgery centers. Therefore, unplanned delayed surgery was more common in China, which differed from the situation in higher-income economies.
On the other hand, delayed surgery has several advantages compared to immediate surgery. Either the difficulty of procedures or the postoperative mortality and morbidity all declined significantly in delayed surgery7. As preoperative mechanical assistance got popular, delayed surgery was accepted gradually by some centers8,9. The 2017 ESC guidelines for STEMI suggest that delayed surgery could be considered for patients who respond well to aggressive treatment10.
Risk factors for postoperative 30-days mortality including advanced age, female gender, renal dysfunction, cardiogenic shock, decreased EF, three-branch lesions, and unstable status requiring preoperative IABP have been identified in the previous researches6. Other research found that larger ruptures are more likely to cause preoperative cardiogenic shock7, but no direct correlation between rupture size and postoperative mortality was reported. However, only a few studies about delayed surgery for VSR were reported, and the majority were case reports and case series. Previous studies left a gap in risk factors analysis of delayed surgery for VSR. In this study, we aim to find the independent risk factors of delayed VSR repair by reviewing the clinical data of VSR patients in our center and analyze the impact of rupture size on the critical preoperative status and surgical outcomes.