Non-invasive cardiac mapping for non-response in cardiac resynchronization therapy

Abstract

Cardiac resynchronization therapy (CRT) is an effective intervention in selected patients with moderate-to-severe heart failure with reduced ejection fraction and abnormal left ventricular activation time. The non-response rate of approximately 30% has remained nearly unchanged since this therapy was introduced 25 years ago. While intracardiac mapping is widely used for diagnosis and guidance of therapy in patients with tachyarrhythmia, its application in characterization of the electrical substrate to elucidate the mechanisms involved in CRT response remain anecdotal. In the present review, we describe the traditional determinants of CRT response before presenting novel non-invasive techniques used for CRT optimization. We discuss efforts to identify the target electrical substrate to guide the deployment of pacing electrodes during the operative procedure. Non-invasive body surface mapping technologies such as ECG imaging or ECG belt enables prediction of acute and chronic CRT response. While electrical dyssynchrony parameters provide high predictive accuracy for CRT response when obtained during intrinsic conduction, their predictive value is less when acquired during CRT or LV-pacing. KEY MESSAGES Classic predictors of CRT response are female gender, NYHA class III, left ventricular ejection fraction !25%, QRS duration !150 ms and estimated glomerular filtration rate !60 mL/min. ECG-imaging is a comprehensive non-invasive mapping system which allows to express the amount of electrical asynchrony of a CRT candidate. Non-invasive body surface mapping technologies enables excellent prediction of acute and chronic CRT response before implantation. When performed during CRT or LV-pacing, the added value of these mapping systems remains unclear.

Cardiac resynchronization therapy with intraoperative epicardial mapping via minithoracotomy: 10 years’ experience

“…It is interesting that in spite of several studies 8,26,29 considering female gender as a positive predictor of CRT responderity, there were no significant gender differences in Kaplan‐Meier survival estimate found by Tarone‐Ware test (Figure 2B) or in the forest plot (Figure 3B) in the present investigation, however, limitations due to the small number of cases must be taken into consideration. However, the female line is throughout a bit above the male line on Figure 2B, nevertheless, the small number of the patients can smudge the difference.…”

“…After an efficient CRT, the patients’ functional capacity, complaints, hospitalization rate, and survival improve significantly compared to medical therapy alone, 3,4,9,10,20–22 and, on the other hand, CRT therapy allows better optimization of medical treatment in heart failure patients 23 . Nevertheless, in spite of appropriate positioning of the LV electrode, roughly one third of the patients are nonresponders to epicardial 24–26 or endocardial 12 CRT. However, there is no uniform definition of CRT response, 27 which would be essential in order to compare different studies.…”

Electrocardiographic imaging of His bundle, left bundle branch, epicardial, and endocardial left ventricular pacing to achieve cardiac resynchronization therapy

“…Noninvasive cardiac mapping using electrocardiographic imaging (ECGi) is a method of assessing ventricular activation and has been used in the CRT population to predict and assess response, guide LV lead placement, and optimize therapy. 1 , 2 , 3 , 4 In this report we describe the electrical effects of these different pacing modalities using ECGi.…”

Ultra-High-Frequency ECG in Cardiac Pacing and Cardiac Resynchronization Therapy: From Technical Concept to Clinical Application

“…Over the past decade, various alternative methods of ventricular dyssynchrony assessment have been proposed. These range from simple options such as vectorcardiography [ 9 , 10 , 11 ] and ultra-high-frequency ECG (UHF-ECG) to more advanced techniques like ECG-belt [ 12 , 13 , 14 , 15 ], ECG-imaging [ 16 , 17 , 18 , 19 , 20 , 21 ] and electro-anatomic mapping [ 6 , 22 , 23 , 24 , 25 , 26 ] ( Figure 1 ).…”