Why We Have to Use Cardiac Resynchronization Therapy-Pacemaker More

Predicting defibrillator benefit in patients with cardiac resynchronization therapy: A competing risk study

BACKGROUND

Cardiac resynchronization therapy (CRT) reduces morbidity and mortality in selected heart failure patients, but decision-making regarding selection of CRT-defibrillator or CRT-pacemaker is an ongoing debate.

OBJECTIVE

The purpose of this study was to construct predictive models and scoring systems for implantable cardioverter-defibrillator (ICD) therapy and death without ICD therapy (prior death).

METHODS

We pooled 2 prospective cohorts of CRT-D patients with primary prevention indication and used Fine and Gray models to develop independent prognostic models for time to first ICD therapy (event of interest) or death without prior ICD therapy (competing event). We defined CRT-D benefit as a high probability of ICD therapy combined with moderate/low probability of prior death.

RESULTS

Seven hundred twenty patients were included. Median follow-up was 7.2 years, and 247 patients (34%) died. Cumulative incidence of ICD therapy/prior death at 5 years was 24%/17%. In multivariable models, higher New York Heart Association classes, diuretic use, and ischemic cardiomyopathy were predictors of ICD therapy (hazard ratio 1.89 [1.30-2.75], 1.91 [1.12-3.24], and 1.40[1.02-1.92], respectively) but not of prior death. Males with comorbidities (cancer, renal failure, peripheral artery disease, body mass index >30) or systolic blood pressure ≤100 were at higher risk for prior death. Higher age was associated with lower risk of ICD therapy but higher risk of prior death. One-quarter of patients had low predicted benefit from CRT-D implantation using a scoring system for the dual prediction of appropriate ICD therapy and death without appropriate ICD-therapy.

CONCLUSION

Different factors predict ICD therapy or prior death in CRT-D patients using competing risk models. Scoring allows identifying patients with predicted low benefit of CRT-D (low chance of ICD therapy, high chance of prior death).

Predictors for early mortality and arrhythmic events in patients with cardiac resynchronization therapy with defibrillator: A two center cohort study

BACKGROUND

Guidelines of heart failure therapy include cardiac resynchronization as standard of care in patients with severely depressed left ventricular function and wide QRS complex. It has been shown that patients benefit regarding mortality and morbidity. However, early mortality precludes longterm benefits from the device. The aim of the study was to identify predictors for early occurrence of both death and first-ever implantable cardioverter-defibrillator (ICD) therapy using a large combined database of patients with cardiac resynchronization therapy with defibrillator (CRT-D).

METHODS

From two registries (tertiary care centers) 904 patients were identified, no single patient was excluded. Early death was defined as death occurring within the 3 years after implantation whereas early ICD therapy as such occurring within the first year. 33 baseline parameters were compared using uni- and multivariate analysis with the Cox model and binary logistic regression.

RESULTS

The population was predominantly male (77%), with mean age of 63 ± 11 years and primary prevention indication in 80%. Mean follow-up was 55 ± 38 months. 256 (28%) patients had ICD therapies whereof the first-ever event occurred early in 52%. 270 (30%) patients died after 41 ± ± 31 months, mostly from advancing heart failure (41%), 141 (52%) patients of them early. Independent predictors for early ICD therapy were secondary prevention and renal failure. Independent predictors for early mortality were a history of percutaneous coronary intervention and of peripheral vascular disease.

CONCLUSIONS

Predictors for early mortality after CRT-D implantation were a history of percutaneous coronary intervention and peripheral vascular disease, present in only a minority of patients, thus limiting their use in clinical practice.

Realizing zT of 2.3 in Ge1-x-y Sbx Iny Te via Reducing the Phase-Transition Temperature and Introducing Resonant Energy Doping

GeTe with rhombohedral-to-cubic phase transition is a promising lead-free thermoelectric candidate. Herein, theoretical studies reveal that cubic GeTe has superior thermoelectric behavior, which is linked to (1) the two valence bands to enhance the electronic transport coefficients and (2) stronger enharmonic phonon-phonon interactions to ensure a lower intrinsic thermal conductivity. Experimentally, based on Ge_1-x Sb_x Te with optimized carrier concentration, a record-high figure-of-merit of 2.3 is achieved via further doping with In, which induces the distortion of the density of states near the Fermi level. Moreover, Sb and In codoping reduces the phase-transition temperature to extend the better thermoelectric behavior of cubic GeTe to low temperature. Additionally, electronic microscopy characterization demonstrates grain boundaries, a high-density of stacking faults, and nanoscale precipitates, which together with the inevitable point defects result in a dramatically decreased thermal conductivity. The fundamental investigation and experimental demonstration provide an important direction for the development of high-performance Pb-free thermoelectric materials.