A clinical-in silico study on the effectiveness of multipoint bicathodic and cathodic-anodal pacing in cardiac resynchronization therapy.

Up to one-third of patients undergoing cardiac resynchronization therapy (CRT) are nonresponders. Multipoint bicathodic and cathodic-anodal left ventricle (LV) stimulations could overcome this clinical challenge, but their effectiveness remains controversial. Here we evaluate the performance of such stimulations through both in vivo and in silico experiments, the latter based on computer electromechanical modeling. Seven patients, all candidates for CRT, received a quadripolar LV lead. Four stimulations were tested: right ventricular (RVS); conventional single point biventricular (S-BS); multipoint biventricular bicathodic (CC-BS) and multipoint biventricular cathodic-anodal (CA-BS). The following parameters were processed: QRS duration; maximal time derivative of arterial pressure (dPdtmax); systolic arterial pressure (Psys); and stroke volume (SV). Echocardiographic data of each patient were then obtained to create an LV geometric model. Numerical simulations were based on a strongly coupled Bidomain electromechanical coupling model. Considering the in vivo parameters, when comparing S-BS to RVS, there was no significant decrease in SV (from 45 ± 11 to 44 ± 20 ml) and 6% and 4% increases of dPdtmax and Psys, respectively. Focusing on in silico parameters, with respect to RVS, S-BS exhibited a significant increase of SV, dPdtmax and Psys. Neither the in vivo nor in silico results showed any significant hemodynamic and electrical difference among S-BS, CC-BS and CA-BS configurations. These results show that CC-BS and CA-BS yield a comparable CRT performance, but they do not always yield improvement in terms of hemodynamic parameters with respect to S-BS. The computational results confirmed the in vivo observations, thus providing theoretical support to the clinical experiments.

COVID-19 therapies and their impact on QT interval prolongation: A multicentre retrospective study on 196 patients.

BACKGROUND: SARS-CoV-2 infection has caused a global pandemic. Many of the medications identified to treat COVID-19 could be connected with QTc prolongation and its consequences. METHODS: Non-ICU hospitalized patients of the three centres involved in the study from the 19th of March to the 1st of May were included in this retrospective multicentre study. Relevant clinical data were digitally collected. The primary outcome was the incidence of QTc prolongation ≥ 500 ms, the main secondary outcomes were the Tisdale score ability to predict QTc prolongation and the incidence of ventricular arrhythmias and sudden deaths. RESULTS: 196 patients were analysed. 20 patients (10.2%) reached a QTc ≥ 500 ms. Patients with QTc ≥ 500 ms were significantly older (66.7 ± 14.65 vs 76.6 ± 8.77 years p: 0.004), with higher Tisdale score (low 56 (31.8%) vs 0; intermediate 95 (54.0%) vs 14 (70.0%); high 25 (14.2%) vs 6 (30.0%); p: 0.007) and with higher prognostic lab values (d-dimer 1819 ± 2815 vs 11486 ± 38554 ng/ml p: 0.010; BNP 212.5 ± 288.4 vs 951.3 ± 816.7 pg/ml p < 0.001; procalcitonin 0.27 ± 0.74 vs 1.33 ± 4.04 ng/ml p: 0.003). After a multivariate analysis the Tisdale score was able to predict a QTc prolongation ≥ 500 ms (OR 1,358 95% CI 1,076-1,714p: 0,010). 27 patients died because of COVID-19 (13.7%), none experienced ventricular arrhythmias, and 2 (1.02%) patients with concomitant cardiovascular condition died of sudden death. CONCLUSIONS: In our population, a QTc prolongation ≥ 500 ms was observed in a minority of patients, no suspected fatal arrhythmias have been observed. Tisdale score can help in predicting QTc prolongation.