Electrocardiographic and angiographic features in cardiogenic shock

Cardiogenic shock (CS) is a medical emergency in which cardiac dysfunction causes a state of shock resulting in end-organ hypoperfusion. The most common cause of CS is acute coronary syndrome (ACS), ST-segment elevation myocardial infarction (STEMI) being the leading aetiology. Other causes of CS may include exacerbation of chronic heart failure, valvular dysfunction, myocarditis, and stress-induced cardiomyopathy. Despite progress in revascularization and development of mechanical circulatory support-devices, short-term mortality is still high at 40%, which calls for further advances in CS management and in risk stratification. The electrocardiogram (ECG) plays a major role at the first instance of CS management, as it provides essential information about cardiac ischaemia, rhythm, and conduction. After initial evaluation, emergent coronary angiography is the next step in CS management with the possibility of immediate revascularization with percutaneous coronary intervention (PCI). The aim of this study was to examine electrocardiographic and angiographic features in CS. The patient data in this thesis are primarily included in a multinational, prospective, observational cohort study called the CardShock study, which investigated 219 CS patients with diverse CS aetiologies. Study I evaluated baseline ECG ST-segment patterns in patients with differing CS aetiologies. ST-segment elevation was associated with ACS, and in patients with ST-segment elevation, CS was often the first manifestation of coronary artery disease. One-third of patients with ST-segment depression did not have ACS, but ST-segment depression was associated with a high burden of previous comorbidities. ST-segment elevation was associated with 90-day mortality in patients with mixed CS aetiologies. In the subgroup of ACS patients, no difference in revascularization or mortality rates emerged between the studied ST-segment patterns. Study II examined ventricular conduction disturbances in patients with ACS-related CS. In this population, ventricular conduction disturbances occurred more often in older patients with a higher burden of comorbidities. The temporal evolution of ventricular conduction blocks from baseline to day three was high, because one-third of the blocks were transient. All ventricular conduction disturbances were associated with poor prognosis, and the reversal of the block during the first three days was not associated with better one-year survival. Study III examined the prognostic value of the SYNTAX scores in STEMI-related CS patients. The SYNTAX score is a tool created for assessment of the complexity of coronary artery disease. In this study, SYNTAX score was calculated before PCI (baseline SYNTAX score) and after PCI (residual SYNTAX score). The baseline SYNTAX score was associated with mortality, but its additive value in risk prediction beyond clinical assessment and risk scores was marginal. Residual SYNTAX score did not associate with outcome in STEMI-related CS. Study IV examined angiographic features and their prognostic value in ACS-related CS. Multivessel disease and unsuccessful revascularization of the infarct-related artery were associated with poor prognosis. In addition, assessment of procedural PCI complications showed that arrhythmic complications were the most common, but they did not associate with worse outcome. In conclusion, electrocardiography is an important tool for differentiating the aetiologies of CS and it can be useful in risk assessment. ST-segment elevation and ventricular conduction blocks are markers of high mortality risk. In addition, some angiographic features may prove useful in prognosis assessment. Multivessel disease carries a high mortality risk, whereas successful revascularization of the infarct-related artery is associated with better outcome.