Intracoronary ECG ST-segment Shift Remission Time During Reactive Coronary Hyperemia, τ-icECG: a New Method for Assessing Hemodynamic Stenosis Severity

Cardiovascular disease is the major cause of death globally, accounting for 17.9 million deaths per year in 2019. Aside from the acute coronary syndrome, where percutaneous coronary intervention (PCI) has been shown to improve outcome, the number of patients with chronic coronary syndrome (CCS) is also increasing. PCI of hemodynamically relevant stenotic lesions causing myocardial ischemia is the standard treatment in these patients. Effective revascularization, as recommended by the European Society of Cardiology (ESC) guidelines, requires to differentiate between hemodynamically relevant and non-significant stenotic coronary lesions.

Currently, coronary stenosis assessment is performed by structural visual angiographic assessment or by coronary pressure measurements up- and downstream of the lesion. The latter is recommended by the ESC and is based on its prognostic value derived from large randomized clinical trials. Given temporary paralysis of the coronary microcirculation by a hyperemia-inducing substance such as adenosine (ADO), pressure is, in theory, directly related to coronary flow. Therefore, the pressure drop during hyperemia across a coronary stenosis, i.e., fractional flow reserve (FFR) provides an estimate of its restrictive effect on flow. However, this method depends on expensive pressure sensor angioplasty guidewires, and on hyperemia-inducing substances, such as ADO. Hence, pharmacologic limitations such as atrioventricular conduction defects and asthma and other potential adverse events (e.g. arrhythmias) aside from costs are major drawbacks of pressure-derived FFR. In order to avoid potential drug-induced side effects and achieve maximal hyperemia, the study group performs reactive hyperemia FFR measurements induced by a proximal, 1-minute coronary artery balloon occlusion. This method has been documented non-inferior in its ability to detect relevant coronary stenosis compared to adenosine-induced FFR.

The present project aims at validating a novel, potentially more harmless, faster and less costly diagnostic approach for measuring hemodynamic coronary stenosis severity.

The commonly obtained surface lead electrocardiogram (ECG) is limited in detecting short-lasting or minor myocardial ischemia. In comparison, intracoronary ECG (icECG) is more time- and space-sensitive in detecting myocardial ischemia, the latter being due to its close vicinity to the myocardial region of interest. It can be easily obtained by attaching an alligator clamp to a coronary guidewire.

Based on the sensitivity of the icECG, several clinical trials have assessed the value of icECG to guide PCI, and rated it useful to predict post-procedural myocardial injury.