Incremental Value of Right Ventricular Outflow Tract Diameter in Risk Assessment of Chronic Heart Failure Patients with Implantable Cardioverter Defibrillators: Development of RVOTD-ICD Benefit Score in Real-World Setting

TL;DR

This study shows that measuring the right ventricular outflow tract diameter (RVOTD) improves risk assessment for heart failure patients considering implantable cardioverter defibrillators (ICDs).

Contribution

The novel contribution is the development of the RVOTD-ICD benefit score, a new risk assessment tool incorporating RVOTD for better ICD decision-making.

Findings

Higher RVOTD was significantly linked to increased risk of ventricular tachycardia/fibrillation (VT/VF) but not non-arrhythmic mortality.

The RVOTD-ICD benefit score outperformed existing tools in predicting VT/VF and mortality risks in heart failure patients.

The highest benefit group had an 8-fold higher risk of VT/VF compared to non-arrhythmic mortality over three years.

Abstract

Left ventricular ejection fraction (LVEF) remains the basic
reference for the prevention of sudden cardiac death (SCD) patients, while right
ventricular (RV) abnormalities have now been associated with SCD risk. A modified
benefit assessment tool incorporating RV function parameters in consideration of
implantable cardioverter defibrillators (ICD) insertion should be taken into
account.

We enrolled 954 chronic heart failure (CHF) patients
(age 58.8 ± 13.1 years; 79.0% male) with quantitative measurements of
right ventricular outflow tract diameter (RVOTD) before ICD implantation and then
divided them according to the median level of RVOTD. The predictive value of
RVOTD in life-threatening ventricular tachycardia (VT)/ventricular fibrillation
(VF) vs. non-arrhythmic mortality (defined as death without prior sustained
VT/VF), was evaluated respectively. Based on RVOTD and other identified risk
factors, a simple risk assessment tool, RVOTD-ICD benefit score, was developed.

A higher RVOTD level was significantly associated with an
increased risk of VT/VF (per 1 standard deviation (SD) increase, hazard ratio [HR], 1.22; 95%
confidence interval [CI], 1.11–1.33; p = 0.002) but not non-arrhythmic
mortality (per 1 SD increase, hazard ratio, 0.93; 95% CI, 0.66–1.33; p
= 0.709) after multivariable adjustment. Three benefit groups were created based
on RVOTD-ICD benefit score, which was calculated from VT/VF score (younger age,
higher RVOTD, diuretic use, prior non-sustainable VT, prior sustainable VT/VF)
and non-arrhythmic mortality scores (older age, renin-angiotensin-aldosterone
system inhibitors use, diabetes, higher left ventricular end-diastolic diameter,
New York Heart Association III/IV, higher N-terminal pro-B-type natriuretic
peptide levels). In the highest RVOTD-ICD benefit group, the 3-year risk of VT/VF
was nearly 8-fold higher than the corresponding risk of non-arrhythmic mortality
(39.2% vs. 4.8%, p
< 0.001). On the contrary, the 3-year risk of
VT/VF was similar to the risk of non-arrhythmic mortality (21.9% vs. 21.3%,
p = 0.405) in the lowest benefit group. RVOTD-ICD benefit score system
yielded improvement in discrimination for VT/VF, non-arrhythmic mortality, and
all-cause mortality than Multicenter Automatic Defibrillator Implantation Trial (MADIT)-ICD benefit score in this cohort.

Higher RVOTD was associated with
significantly increased risk of sustained VT/VF in CHF patients. A simple risk
assessment tool incorporating RVOTD (RVOTD-ICD benefit score) could be
generalized to ICD populations, and optimize the decision-making process of ICD
implantation.

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