Coronary flow reserve is the capacity of the coronary circulation to augment the blood flow in response an increase in myocardial metabolic demands and has a powerful prognostic significance in different clinical situations. It might assess with invasive and non-invasive technique. Transthoracic echocardiography Doppler is an emerging diagnostic technique, noninvasive, highly feasible, safe for patient and physician, without radiation, able to detect macrovascular and microvascular anomalies in the coronary circulation. This review aims to describe the benefit and limits of noninvasive assessment of coronary flow reserve, in particular his evaluation with echocardiography.

Introduction: no data are provided about the effect of triple combination therapy with Lopinavir/Ritonavir (LPN/RTN), hydroxychloroquine (HQ) and azithromycin (AZT) on corrected QT (QTc) interval and arrhythmic risk, in COVID-19 patients. This study aims to describe the incidence of extreme QTc interval prolongation among COVID-19 patients on this experimental treatment and to identify the clinical features associated with extreme QTc prolongation. Materials and methods: data of 87 COVID-19 patients, treated with triple combination including LPN/RTN, HQ and AZT, were analyzed. QT interval was obtained by the tangent method and corrected for heart rate using Bazett’s formula. Extreme QTc interval prolongation was considered an absolute QTc interval ≥ 500 ms or an increase in QTc intervals of 60 milliseconds or greater (ΔQTc ≥ 60 milliseconds) compared with baseline. Results: Hypertension (66.7%) and diabetes (25.3%) were the most prevalent cardiovascular comorbidities. 20 patients (23%) showed extreme QTc interval prolongation; No clinical, electrocardiographic or pharmacological characteristics have been associated to extreme QTc prolongation, except the history of ischemic stroke (P= 0,007). One torsade de pointes (TdP) in patient with QTc extreme prolongation (QTc: 560 ms) after 5 days of therapy was recorded. Conclusions: We observed a high incidence of extreme QTc interval prolongation among COVID-19 patients on triple combination therapy. The incidence of malignant arrhythmias seems to be low, a careful electrocardiographic monitoring would be advisable.