Other risk factors include hypertension during the acute phase of STEMI, lack of ante- cedent angina or prior MI, absence of collateral blood flow, Q waves on ECG, use of corticosteroids or nonsteroidal anti-inflammatory drugs, and administration of fibrinolytic therapy >14 hours after symptom onset.485,486 Pseudoaneu- rysm formation with contained rupture and tamponade can be recognized with transthoracic echocardiography, and emergency surgery should be considered. Most case series of patients reaching the operating room for management of this complication are of small size, with mortality rates 9.4.5. LV Aneurysm Ventricular aneurysm formation after STEMI occurs in <5% of patients and is more frequent in those with anterior infarc- tion. Incidence rates have declined with timely reperfusion. Surgery for LV aneurysm after STEMI is rarely needed but may be considered for treatment of HF, ventricular arrhyth- mias not amenable to drugs or radiofrequency ablation, or recurrent thromboembolism despite appropriate anticoagulant therapy. 9.5. Electrical Complications During the Hospital Phase of STEMI 9.5.1. Ventricular Arrhythmias Ventricular arrhythmias are common early after onset of STEMI, and not all require intervention. Out-of-hospital cardiac arrest with STEMI is most often due to lethal ven- tricular arrhythmias, including sustained VT and VF (Sec- tion 3.6.1). The mechanisms for these arrhythmias are multifactorial and include ongoing ischemia, hemodynamic and electrolyte abnormalities, reentry, and enhanced auto- maticity. 