Noninvasive Electrical Mapping Compared with the Paced QRS Complex for Optimizing CRT Programmed Settings and Predicting Multidimensional Response

Abstract

The aim was to test the hypothesis that left ventricular (LV) and right ventricular (RV) activation from body surface electrical mapping (CardioInsight 252-electrode vest, Medtronic) identifies optimal cardiac resynchronization therapy (CRT) pacing strategies and outcomes in 30 patients. The LV80, RV80, and BIV80 were defined as the times to 80% LV, RV, or biventricular electrical activation. Smaller differences in the LV80 and RV80 (|LV80-RV80|) with synchronized LV pacing predicted better LV function post-CRT (p = 0.0004) than the LV-paced QRS duration (p = 0.32). Likewise, a lower RV80 was associated with a better pre-CRT RV ejection fraction by CMR (r = - 0.40, p = 0.04) and predicted post-CRT improvements in myocardial oxygen uptake (p = 0.01) better than the biventricular-paced QRS (p = 0.38), while a lower LV80 with BIV pacing predicted lower post-CRT B-type natriuretic peptide (BNP) (p = 0.02). RV pacing improved LV function with smaller |LV80-RV80| (p = 0.009). In conclusion, 3-D electrical mapping predicted favorable post-CRT outcomes and informed effective pacing strategies.

Keywords: Cardiac magnetic resonance; Cardiac resynchronization therapy; Electrical mapping; Heart failure; Right ventricular function.

Fig. 1

CRT electrical activation parameters. a Differences in intrinsic RV80, LV80, and BIV80 are shown for LBBB and RBBB. b-d Variability in electrical activation based on LBBB and RBBB are shown for b LV80, c RV80, and d BIV80, and the slope for each relationship for each case, such that a difference is slopes, indicates a non-constant rate of electrical activation throughout the QRS duration

Fig. 2

Sample variable electrical activation curves. Typical electrical activation curves demonstrating variability of activation are shown for patients with LBBB (a) and RBBB (b). The plots for the proportion of electrical activation versus time are not linear, which demonstrates non-constant electrical activation through the QRS duration

Fig. 3

Effects of pacing on linearity of electrical activation for the RV and LV. a LV80, b RV80, and c BIV80 are plotted versus QRS duration for LV pacing. Similar plots are shown for BIV pacing in d–f. Compared with Fig. 1, the slopes for RBBB and LBBB are more consistent with LV pacing and BIV pacing

Fig. 4

Pacing configuration plots. Novel pacing configuration plots are shown for easy visualization of electrical activation of the RV and LV for different pacing modes, such as BIVP and LVP. These plots demonstrate the extent to which the RV80 and LV80 shorten or lengthen relative to the intrinsic rhythm and the similarity between the RV80 and LV80 with each mode, as a measure of electrical interventricular synchrony

Fig. 5

Associations of electrical chamber-specific baseline parameters with CRT outcomes. The fractional change in the LVESVI (multiplied by 100 to give a percentage) with LVP is plotted versus the absolute difference between LV80 and RV80 with LVP in b, and the comparison with QRS duration is provided in d. Corresponding plots for 70% and 90% activation are shown in a and c, respectively. The fractional change in the LVESVI with RVP is plotted versus the absolute difference between the LV80 and RV80 with RVP in f, and the comparison with QRS duration is provided in h. Corresponding plots for 70% and 90% activation are shown in e and g, respectively. The log of the post-CRT BNP is plotted versus the LV80 with biventricular pacing in j, and the comparison with QRS duration is provided in l. Corresponding plots for 70% and 90% activation are shown in i and k, respectively. The peak VO₂ is plotted versus the fractional change in the RV80 (also multiplied by 100 to give a percentage) with n biventricular pacing, and the comparison with QRS duration is provided in p. Corresponding plots for 70% and 90% activation are shown in m and o, respectively

Fig. 6

Associations with RV electrical activation and CMR-based RV function. Scatter plots of the baseline RVEF versus the RV80 (a), RVEF versus RV80/QRS (b), and RVEF versus QRS (c) are shown. The strongest associations were found with the RV80 and RV80/QRS duration at baseline