Usefulness of the Sum Absolute QRST Integral to Predict Outcomes in Patients Receiving Cardiac Resynchronization Therapy

Abstract

Cardiac resynchronization therapy (CRT) reduces mortality and morbidity in selected heart failure (HF) patients, but up to one-third of patients are non-responders. Sum absolute QRST integral (SAI QRST) recently showed association with mechanical response on CRT. However, it is unknown whether SAI QRST is associated with all-cause mortality and HF hospitalizations in CRT patients. The study population included 496 patients undergoing CRT (mean age 69±10 years, 84% male, 65% left bundle branch block (LBBB), left ventricular ejection fraction 23±6%, 63% ischemic cardiomyopathy). Pre-implant digital 12-lead ECG was transformed into orthogonal XYZ ECG. SAI QRST was measured as an arithmetic sum of areas under the QRST curve on XYZ leads, and was dichotomized based on the median value (302mV*ms). All-cause mortality served as the primary endpoint. A composite of 2-year all-cause mortality, heart transplant, and HF hospitalization was a secondary endpoint. Cox regression models were adjusted for known predictors of CRT response. Patients with pre-implant low mean SAI QRST had an increased risk of both the primary (HR 1.8; 95%CI 1.01–3.2) and secondary (HR 1.6, 95% CI 1.1–2.2) endpoints following multivariable adjustment. SAI QRST was associated with secondary outcome in subgroups of patients with LBBB (HR 2.1 [95%CI 1.5-3.0]) and with non-LBBB (HR 1.7, [95%CI 1.0-2.6]). In patients undergoing CRT, pre-implant SAI QRST<302mV*ms was associated with an increased risk of all-cause mortality and HF hospitalization. After validation in another prospective cohort, SAI QRST may help to refine selection of CRT recipients.

Baseline adverse electrical remodeling and the risk for ventricular arrhythmia in Cardiac Resynchronization Therapy Recipients (MADIT CRT)

“…Hard clinical endpoints were also evaluated in a recent retrospective analysis of patients receiving CRT in a large tertiary center in Sweden . Preimplant SAI QRST of <302 mV ms was associated with 60–70% increase in risk of all‐cause mortality and HF hospitalization independent of QRS morphology.…”

Global Electrical Heterogeneity: Mechanisms and Clinical Significance

“…The sum absolute QRST integral (SAI QRST) is a scalar analog of the SVG [3][4][5][6], associated with ventricular tachyarrhythmias in heart failure. [3,4,7] SAI QRST is associated with electrical dyssynchrony [8], mechanical response to cardiac resynchronization therapy [9], and mortality in cardiac resynchronization therapy patients [10]. Patient-specific time-varying associations between SAI QRST and high sensitivity troponin I suggest that SAI QRST reflects subclinical myocardial injury.…”

Adaptive Cardiac Resynchronization Therapy Effect on Electrical Dyssynchrony (aCRT-ELSYNC): a randomized controlled trial

“…The copyright holder for this this version posted September 15, 2020. ; https://doi.org/10.1101/2020.09.14.20194415 doi: medRxiv preprint post-CRT, and (2) surface ECG/VCG metric, sum absolute QRST integral (SAIQRST), 14,15 is a superior estimate of electrical dyssynchrony as compared to QRS duration. The secondary objective was to determine if aCRT is associated with improvement in the quality of life and other clinically important outcomes.…”