Evaluation of Mortality and Hospitalization Due to Decompensated Heart Failure and Appropriate Shocks in Reduced Ejection Fraction in Patients with an Implantable Cardioverter–Defibrillator According to a Novel Tissue Doppler Echocardiographic Method

<b>Background/Objectives:</b> Heart failure is a very common disease, and its incidence is increasing. Echocardiography is a non-invasive tool frequently used in the diagnosis and risk stratification of heart failure. In our study, we aimed to evaluate the risk of all-cause mortality, hospitalization due to decompensated heart failure, and appropriate shocks in reduced ejection fraction patients (HFrEF) with an implantable cardioverter-defibrillator (ICD) according to a novel tissue Doppler echocardiographic parameter that reflects pulmonary capillary wedge pressure. <b>Methods</b>: A total of 320 HFrEF patients with ICD were included in the study between 1 February 2021 and 30 June 2023, from the cardiology outpatient clinic and cardiology ward. Using tissue Doppler, the peak systolic velocity (ST) at the free wall side of the tricuspid annulus and the peak systolic velocity (SM) at the lateral side of the mitral annulus were measured, and the ratio of ST to SM (ST/SM) was calculated. The inferior vena cava diameter (IVCDi) was measured during inspiration. These two values were multiplied to form the formula IVCDi × (ST/SM). Based on the IVCDi × (ST/SM) value, patients were divided into two groups: those with high values (>17, <i>n</i> = 144) and those with low values (≤17, <i>n</i> = 176). The primary endpoint of our study was all-cause mortality, and the secondary endpoint was major adverse cardiovascular events (MACE), including appropriate shocks, hospital admission due to acute heart failure decompensation, and mortality. <b>Results</b>: Long-term mortality was higher in the high IVCDi × (ST/SM) group compared to the low-value group (44% vs. 15%, <i>p</i> < 0.001). The MACE frequency was also higher in patients with high IVCDi × (ST/SM) values (71% vs. 30%, <i>p</i> < 0.001). In multivariable analysis, IVCDi × (ST/SM) was an independent predictor of both mortality (HR: 1.027, 95%CI: 1.009-1.046, <i>p</i> = 0.003), and MACE (HR: 1.018, 95%CI: 1.004-1.032, <i>p</i> = 0.013). <b>Conclusions</b>: We demonstrated that the IVCDi × ST/SM value, a novel tissue Doppler echocardiographic parameter, is an independent predictor of both long-term mortality and major adverse cardiac events (MACE) in HFrEF patients with ICD. This parameter may be valuable in identifying high-risk patients and optimizing their treatment management.