Abstract
Background
Cardiac resynchronization therapy (CRT) has demonstrated efficacy in at least 60% of patients with left ventricular (LV) failure and guideline-based indication to CRT. Whereas lack of response to CRT in up to a third of patients is multifactorial, a relevant factor is thought to be inadequate biventricular pacemaker (BIV) optimization (OPT) of either the intraventricular (VVd) or atrioventricular (AVd) delay
Purpose
In this echocardiographic observational study, we compared the acute effects on LV contractility, output, and diastolic function of BIV intra-implant QRS duration-based (OPTq) and post-implant Doppler echocardiography-based (OPTe) OPT of VVd and AVd.
Methods
In 160 patients with ischemic (n = 86) or idiopathic (n = 74) dilated cardiomyopathy, guideline-based different de novo CRT systems were implanted followed by immediate OPTq. Post-implant (10 days) OPTe was performed measuring: transmitral velocity-time integral (MVFi), % diastolic filling time (MVFt%), and E/A ratio, LV outflow integral (LVOTi), ejection time (LVOTt), and stroke volume (SV), isovolumic contraction (IVCT) and relaxation (IVRT) times, and LV myocardial performance index (MPI). The protocol included, sequentially: 1) Doppler measurements with OPTq settings; 2) measurements (separated by 3’ intervals) during a range (80/200 ms) of AVd with synchronous VVd; 3) algorithm-based AVd selection (at least 2 of following: increase in MVFi or SV, decrease in MPI); 4) measurements, with set AVd, during range of VVd: LV-first (-20, -40ms); RV-first (20, 40ms); synchronous; 5) VVd selection based on same algorithm used for AVd selection. Results. At OPTq, 58.6% of patients were set synchronous, 38.6% LV-first and 3% RV-first, with a 126 ± 29 mean AVd. This increased to 137 ± 36 after OPTe, when 49.1% were set synchronous, 38% LV-first and 12.4% RV-first, resulting in modifications of AVd and VVd in 59% and 36% of patients. Further, gain in SV with OPTe, compared to OPTq, was 8.3% (p<.001), paralleled by an increase in MVFi (21.2 ± 8 cm vs 20.5 ± 8, p<.001) and decrease in E/A (1.25 vs 1.45, p<.001). The greatest increase in SV with OPTe was found in patients in whom both AVd and VVd were modified (n = 48; 81 ± 26 ml vs 71 ± 23, p<.001) vs. patients without modifications (n = 42), or with change of either AVd or VVd (n = 70; 77 ± 20 vs 72 ± 20, p<.01). Only in the first patient group both MVFi (22 ± 9 vs 20 ± 9, p<.001) and MVFt% (52 ± 7 vs 49 ± 8, p=.004) increased, along with a decrease in MPI (.82±.31 vs .92 ± 36, p=.007) and IVRT (144 ± 51 vs 156 ± 62, p=.02.
Conclusions
These preliminary results point to a significant incremental role of post-implant OPTe to enhance LV output, contractility, and diastolic function in patients with CRT. The prognostic role of OPTe-determined AVd and VVD changes remains to be determined.
Echocardiographic evaluation of cardiac resynchronization therapy
