In Chapter 2 we described the design and rationale of the TRANSIENT trial. The rationale of this study is based on the assumption that a delayed invasive strategy would prevent periprocedural myocardial infarction and would lower myocardial infarct size in patients with transient STEMI. This study randomized 142 patients with transient STEMI to an immediate invasive strategy or an delayed invasive strategy, pending on risk. In Chapter 3 we reported the primary endpoint of the TRANSIENT study, infarct size measured with cardiac magnetic resonance imaging (CMR) at day 4. We found infarct size in general to be small and not different between the immediate and the delayed invasive group. To identify differences between patients with transient STEMI and STEMI we compared the patients from the TRANSIENT study to a cohort of patients with STEMI in Chapter 4. We found that patients with transient STEMI were more often female and had more cardiovascular risk factors than STEMI patients but less thrombus burden on coronary angiography. Furthermore, CMR revealed less microvascular obstruction and a smaller infarct size and a better preserved left ventricular function in patients with transient STEMI. Additionally, we found patients with transient STEMI to be more fibrinolytic, as demonstrated with a reduced clot lysis time, compared to patients with STEMI. Chapter 5 focused on the design and rationale of the COACT trial. In this study we randomized 552 patients with OHCA and restore of spontaneous circulation and in the absence of ST-segment on the ECG to immediate coronary angiography or delayed coronary angiography. We hypothesized that immediate coronary angiography would identify unstable coronary lesions that would benefit from immediate percutaneous coronary intervention (PCI), resulting in improved survival in these high-risk patients. Nevertheless, we did not observe a difference in survival at 90 days, the primary endpoint of the COACT study, between the two treatment strategies. As was described in Chapter 6. Most secondary endpoints, which included neurological outcomes, duration and extent of intensive care support, major bleeding and myocardial injury also did not differ between the treatment groups. We did however observe that patients assigned to the immediate angiography group reached their target temperature later than patients in the delayed angiography group. In Chapter 7, we reported the one-year clinical outcomes of patients in the COACT study. Again, we found no differences between the two treatment strategies with respect to survival, myocardial infarction, revascularization, hospitalization due to heart failure, ICD shocks and patient reported quality of life at one year. In Chapter 8, we describe the CMR and ultrasound evaluation of the left ventricular function of patients in the COACT study. We observed no difference in left ventricular function and dimensions between patients treated with immediate coronary angiography or delayed coronary angiography. In Chapter 9, we investigated sex differences in patients successfully resuscitated from OHCA without ST-segment elevation. We found no sex differences in survival at one year. Women less often had significant coronary artery disease, but when coronary artery disease was present they had worse survival than women without coronary artery disease. This was not observed in men. Finally, in Chapter 10 we addressed the question of optimal targeted temperature management (TTM) in OHCA patients with a shockable rhythm by comparing patients treated with mild therapeutic hypothermia (MTH) (32.0ËšC-34.0ËšC) to targeted normothermia (36.0ËšC-37.0ËšC) in the COACT study. We found no benefit of MTH compared to targeted normothermia on 90-day survival in these patients. Patients in the MTH group had longer intensive care unit (ICU) stay, lower blood pressures, higher lactate levels and increased need for inotropic support.