We read the letter by Szymanski et al and their report on the prognostic impact of ventricular arrhythmias early in the course of ST-elevation myocardial infarction (STEMI) and thank them for their insightful comments. We fully share authors’ interest to the timing of ventricular fibrillation (VF) during the course of acute coronary syndrome as it may indeed have critical importance for the outcome. In our study, we defined reperfusion VF as VF that occurred after infarct-related artery opening but before the end of PCI procedure, on the basis of the information available in medical records. We have addressed the issue of VF timing during the course of STEMI in one earlier study, in which we included 1,718 consecutive patients with STEMI treated by primary percutaneous coronary intervention (PCI). Malignant ventricular arrhythmias were observed in 121 patients and occurred at prehospital stage or before balloon inflation in 60%, accompanied restoration of blood flow in 23% of cases, and in only 17% were registered after the end of PCI. Successfully resuscitated VF in patients discharged alive did not influence their long-term prognosis at 1 year after STEMI.

In general, 96% of life-threatening arrhythmias in our study occurred within the first 24 hours of PCI-treated STEMI. Current recommendations for sudden death prevention still use the 48-hour cutoff for definition of early VF that is not associated with worse long-term outcome. However, that 48-hour cutoff comes from the pre-PCI era. Whether different and possibly shorter cut-offs should be considered for patients who underwent invasive strategy resulting in immediate restoration of coronary flow is not known. Although VF incidence during the first day of STEMI is sufficiently high for evidence-based decisions, the data on prognostic importance of in-hospital VF occurring beyond the first day of STEMI are scarce and can hardly be used for evidence-based risk stratification. Extremely low prevalence of VF after the first day of STEMI would require collaborative research and prospective evaluation to study its prognostic value.