QRS area was strongly associated with echocardiographic and clinical response to cardiac resynchronization therapy, according to a study published in Circulation: Arrhythmia and Electrophysiology.
The relationship between the two was as strong as seen in current patient selection parameters, according to the study.
“Because the QRS area is a simple and objective measurement, it might be an alternative measure for selection of patients for CRT, especially in those patients who do not show a wide [left bundle branch block] QRS complex on their baseline 12-lead ECG,” Antonius M.W. van Stipdonk, MD, of the department of cardiology at Maastricht University Medical Center in the Netherlands, and colleagues wrote.
CRT device implantation
Researchers analyzed data from 1,492 patients (mean age, 67 years; 29% women) who received a CRT device from 2001 to January 2015. Data assessed in the study included baseline digital 12-lead ECG, patient characteristics, device data and left ventricular lead location. ECGs were evaluated for baseline parameters and QRS duration, and QRS area was calculated.
The primary endpoint was a combination of cardiac transplantation, LV assist device implantation and all-cause mortality. Secondary endpoints were LV end-systolic volume reduction at 6 to 12 months after implantation and HF hospitalization within 1 year after CRT device implantation.
The primary endpoint was reached by 31.7% of patients during a mean follow-up of 3.4 years.
The link between QRS area and outcomes was stronger than the relationship between left bundle branch block morphology and QRS duration separately. The relationship was as strong when left bundle branch block morphology and QRS duration were combined.
In receiver operating characteristic curve analysis, QRS area improved the identification of patients who did not achieve the primary endpoint vs. QRS morphology and duration (area under the curve = 0.61 vs. 0.55 and 0.51, respectively; P < .001). QRS area also identified patients with echocardiographic remodeling as a result from CRT compared with QRS morphology and duration (AUC = 0.69 vs. 0.58 and 0.58, respectively; P < .001).
Independent ECG determinant
The only independent ECG determinant linked to the primary endpoint was QRS area (HR = 0.5; 95% CI, 0.35-0.71). There was also a significant association between QRS area and outcomes in patients with and without left bundle branch block and a QRS greater than 150 ms.
“The results from the present study provide important evidence that QRS area is a valuable additional electrocardiographic parameter that can be used to improve patient selection for CRT,” van Stipdonk and colleagues wrote. “Like QRS duration, it can be measured as a continuous variable, whereas the variability in its measurement is likely to be less than in QRS duration. After all, variability in indicating the beginning and end of the QRS complex greatly affects QRS duration but hardly affects QRS area because its value is largely determined by the amplitude of the QRS complex.” – by Darlene Dobkowski
Disclosure: van Stipdonk reports no relevant financial disclosures. Please see the study for all other authors’ relevant financial disclosures.