Cardiac IEDs yield no survival benefit among users after heart transplant

In patients with continuous-flow left ventricular assist devices (CF-LVAD), the use of cardiac implantable electronic devices (CIED) does not seem to impact survival outcomes, according to a new study. On the other hand, cardiac resynchronization therapy with defibrillator (CRT-D) seems to increase the risk of late right ventricular heart failure (RVF).

“Using a large, multicentre international registry we have demonstrated several key findings to advance our understanding of CIED therapy in patients with a CF-LVAD,” the researchers said. “Taken together, these results suggest lack of mortality benefit with CIED and potential increased morbidity in those with CRT and CF-LVAD.”

A total of 524 patients (mean age 52±12 years, 84.4 percent men) in line for heart transplants while being supported by CF-LVADs were enrolled in the study. Majority of the patients (n=388; 74.0 percent) already had CIEDs prior to LVAD implantation, most of which were implantable cardiac defibrillators (ICD; n=239) and CRT-D (n=111). The primary endpoints were survival to transplant and late RVF.

The researchers recorded 113 deaths before heart transplant. Stratifying by CIEDs revealed mortality rates of 24.3 percent, 10.7 percent, and 20.7 percent in patients who had ICDs, CRT-pacemaker (P), and CRT-Ds, respectively. In those who had no CIED and relied on CF-LVADs alone, the pretransplant mortality was 19.9 percent. [Int J Cardiol 2021;doi:10.1016/j.ijcard.2021.08.033]

Over a median follow-up of 354 days, 312 heart transplants occurred: 93 in those without CIEDs and 130, 19, and 70 in patients with ICD, CRT-P, and CRT-D, respectively. Kaplan-Meier analysis showed no significant differences in mortality rates across the groups (log-rank p=0.83). Cox regression analysis further confirmed that neither CIED presence nor type had a significant impact on survival.

Late RVF developed in 72 patients after a median of 189 days: in 11 percent of those with no CIED and in 12.1 percent, 3.6 percent, and 23.4 percent of participants with ICD, CRT-P, and CRT-D, respectively. Kaplan-Meier analysis detected significant differences in the rate of late RVF, particularly between CRT-D and the no-device groups (log-rank p=0.02).

In subsequent logistic regression analysis, after adjustments for covariates, CRT-D almost tripled the risk of late RVF relative to no CIED (hazard ratio, 2.85, 95 percent confidence interval, 1.42–5.72; p=0.003). No such effect was reported for ICD and CRT-P compared with no device.

“The novel finding from the present study was the association with late RVF in those with CRT-D,” the researchers said. “Although our study is not equipped to identify underlying mechanisms of late RVF, we hypothesize that the improved ventricular synchrony with biventricular pacing could paradoxically lead to increased suction events, dynamic obstruction, ventricular arrhythmias, and RVF.”

“A prospective randomized study is needed to determine the role of continued ICD therapy on outcomes and if deactivating the LV lead in patients with pre-existing CRT will mitigate the risk of late RVF in patients with an LVAD,” they added.