Introduction The HF-CGM study is a proof-of-principle study to investigate whether cardiogoniometry (CGM), a three-dimensional electrocardiographic method, can differentiate between pacing modes in patients with cardiac resynchronisation therapy (CRT).

Methods At a tertiary cardiology centre, CGM recordings were performed using four pacing modes: no pacing; right ventricular (RV) pacing; left ventricular (LV) pacing and biventricular (BIV) pacing. Three orthogonal CGM planes orientated to the long axis (XY), the frontal plane (YZ) and the short axis (XZ) of the heart were constructed (see figure), and the direction of the QRS axis was calculated for each pacing mode in each plane. During BIV pacing, the direction of CGM QRS axis was compared between patients with optimal and non-optimal 12-lead ECG pacing variables. Optimally paced 12-lead ECG variables were defined as an R/S ratio greater than or equal to 1 in V₁ and/or R/S ratio less than or equal to 1 in lead I.

Results Eleven participants (aged 77.4±11.5; 63.6% male, LVEF 31±6%) were consecutively recruited. Only QRS axis measured in the XY plane could distinguish between LV and BIV pacing vs. no pacing (p=0.005 and p=0.001 respectively). Mean QRS axis and 95% confidence intervals (CI) for each pacing mode is shown in the table. Mean QRS axis in the XY plane with pacing off and during RV pacing was leftwards and basal; LV pacing was apical; and BIV pacing was rightwards and basal. There was a marked difference in the direction of QRS axis between patients with optimal vs. non-optimal paced QRS morphology in the XY plane (rightwards and basal vs inconsistent).

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Abstract 8 Figure 1

Cardiac CT sections taken in the same approximate sections as the CGM planes – XY plane (panel A), YZ plane (panel B), XZ plane (panel C). Green shading represents the right ventricle; yellow shading represents the left ventricle.

Conclusions CGM recorded in the XY plane can accurately detect differences between ventricular pacing sites. Further studies are needed to determine whether CGM has clinical utility in optimising patients undergoing CRT.