Cardiac Resynchronization Therapy beyond Nominal Settings: An IEGM-Based Approach for Paced and Sensed Atrioventricular Delay Offset Optimization in Daily Clinical Practice

Figures

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  Figure 1. Difference between sensed and paced AV delays. (A) When a sensed P wave occurs, the effective PQ interval (green line) is longer than the sensed AV delay (orange line) because of the latency in atrial sensing (purple line). (B) When a paced P wave occurs, the effective PQ interval (green line) is shorter than the programmed AV delay (red line) because of the latency in atrial capture (blue line). The latency in atrial sensing and atrial capture causes the AV offset delay (blue and purple lines combined).

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  Figure 2. How to calculate the IEGM-based AV offset delay. Line A shows the paced AV delay on the IEGM, which is the time between the atrial pacing spike and the first depolarization of the ventricle. Line B represents the sensed AV delay on the IEGM, which is the time between the onset of atrial depolarization and the first depolarization of the ventricle. The IEGM-based AV offset delay is the difference between line A and line B.

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  Figure 3. Sensed- and paced AV delays in the patient cohort compared to nominal device settings. Optimal atrioventricular (AV) delay offset is plotted for the total study population. Lines represent nominal programmed offset delays of five major manufacturers. A large percentage of patients (>67%) had AV offset delays that exceeded nominal settings.

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  Figure 4. Bland-Altman plot of the difference between the two methods. Bland-Altman plot of differences in optimal AV offset delay measured by echocardiography and by IEGM. Lines and colored areas are indicative of upper and lower limits of agreement (95% confidence interval) and indicate margins of difference between the two techniques (0 ± 30 ms). The size of the dots represents the number of patients. AV, atrioventricular; IEGM, intracardiac electrogram; SD, standard deviation.

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  Figure 5. Correlation between the echocardiography and IEGM determined AV offset delay. The optimal offset between sensed and paced AV delays, obtained from the AV optimization and IEGM calculations, show a good correlation (R2 = 0.62, p < 0.001). The size of the dots represents the number of patients. AV, atrioventricular; IEGM, intracardiac electrogram.