Long-term follow-up of cardiac resynchronization therapy: mechanical resynchronization and reverse left ventricular remodeling are predictive for long-term transplant-free survival

Prognostic value of reverse remodelling criteria in heart failure with reduced or mid-range ejection fraction

Aims

Reverse remodelling (RR) is the recovery from left ventricular (LV) dilatation and dysfunction. Many arbitrary criteria for RR have been proposed. We searched the criteria with the strongest prognostic yield for the hard endpoint of cardiovascular death.

Methods and results

We performed a systematic literature search of diagnostic criteria for RR. We evaluated their prognostic significance in a cohort of 927 patients with LV ejection fraction (LVEF) < 50% undergoing two echocardiograms within 12 ± 2 months. These patients were followed for a median of 2.8 years (interquartile interval 1.3–4.9) after the second echocardiogram, recording 123 cardiovascular deaths. Two prognostic models were defined. Model 1 included age, LVEF, N‐terminal pro‐B‐type natriuretic peptide, ischaemic aetiology, cardiac resynchronization therapy, estimated glomerular filtration rate, New York Heart Association, and LV end‐systolic volume (LVESV) index, and Model 2 the validated Cardiac and Comorbid Conditions Heart Failure score. We identified 25 criteria for RR, the most used being LVESV reduction ≥15% (12 studies out of 42). In the whole cohort, two criteria proved particularly effective in risk reclassification over Model 1 and Model 2. These criteria were (i) LVEF increase >10 U and (ii) LVEF increase ≥1 category [severe (LVEF ≤ 30%), moderate (LVEF 31–40%), mild LV dysfunction (LVEF 41–55%), and normal LV function (LVEF ≥ 56%)]. The same two criteria yielded independent prognostic significance and improved risk reclassification even in patients with more severe systolic dysfunction, namely, those with LVEF < 40% or LVEF ≤ 35%. Furthermore, LVEF increase >10 U and LVEF increase ≥1 category displayed a greater prognostic value than LVESV reduction ≥15%, both in the whole cohort and in the subgroups with LVEF < 40% or LVEF ≤ 35%. For example, LVEF increase >10 U independently predicted cardiovascular death over Model 1 and LVESV reduction ≥15% (hazard ratio 0.40, 95% confidence interval 0.18–0.90, P = 0.026), while LVESV reduction ≥15% did not independently predict cardiovascular death (P = 0.112).

Conclusions

Left ventricular ejection fraction increase >10 U and LVEF increase ≥1 category are stronger predictors of cardiovascular death than the most commonly used criterion for RR, namely, LVESV reduction ≥15%.

Are changes in the extent of left ventricular dyssynchrony as assessed by speckle tracking associated with response to cardiac resynchronization therapy?

Echocardiographic assessment of left ventricular (LV) dyssynchrony is used to predict response to cardiac resynchronization therapy (CRT). However, the association between reduction in the extent of speckle tracking based LV-dyssynchrony and echocardiographic response to CRT has not been explored yet. The aim of this study was to assess the changes in the extent of LV dyssynchrony as a result of CRT and its association with echocardiographic response to CRT in a large consecutive series of patients. We studied 138 patients with standard CRT indication. Time-based speckle tracking longitudinal strain (maximal delay between 6-segments in 4-chamber view) was performed to assess LV-dyssynchrony at baseline and after a mean follow-up of 22 ± 8 months. Echocardiographic CRT response was defined as a reduction in LV end-systolic volume ≥15 %. Mean age was 68 ± 8 years (30 % female). Mean LV ejection fraction (LVEF) was 26 ± 7 %. Ninety six patients (70 %) were classified as echocardiographic responders. In the total study group, LV-dyssynchrony decreased from 196 ± 89 ms at baseline to 180 ± 105 ms during follow-up, P = 0.01. Of note, in responders there was a pronounced reduction in LV dyssynchrony (198 ± 88 ms at baseline vs 154 ± 50 ms after CRT, P < 0.001), whereas in non-responders there was a significant increase (191 ± 92 ms at baseline vs 243 ± 160 ms after CRT, P = 0.04). After multivariate analysis, decreased in LV-dyssynchrony, wider QRS duration and non-ischemic etiology were independently and significantly associated with CRT response. Changes in the extent of LV dyssynchrony as measured by speckle tracking after CRT are independently associated with response to CRT.

Effects of cardiac resynchronization therapy on left ventricular remodeling and dyssynchrony in patients with left ventricular noncompaction and heart failure

Left ventricular noncompaction (LVNC) is a rare cardiomyopathy with high incidence of heart failure (HF). It is unclear whether LVNC patients with desynchronized HF would benefit from cardiac resynchronization therapy (CRT). In order to evaluate the effect of CRT on LVNC, this study explored left ventricular (LV) remodeling and mechanical synchronicity before and after CRT in LVNC patients, and compare with that in idiopathic dilated cardiomyopathy (DCM) patients. We collected 15 LVNC and 30 matched DCM patients. All the patients underwent clinical evaluation,electrocardiogram and echocardiography before CRT and ≥6 months later. LV response was defined as ≥15 % decrease in LV end-systolic volume (LVESV). Longitudinal synchronicity was quantified by YU-index using tissue Doppler imaging. The time delay of peak radial strain from anteroseptal to posterior wall, which derived from speckle tracking imaging, was used to quantify radial synchronicity. In LVNC group, LV ejection fraction increased from 27.6 ± 5.5 to 39.1 ± 7.0 % (P < 0.01) during follow-up, but LV volumes did not change significantly (both P > 0.05). Five LVNC patients (33.3 %) responded to CRT, and all of them were super-responders (reduction in LVESV > 30 %). In addition, the number of noncompacted segments and the thickness ratio of noncompacted to compacted myocardium decreased (both P < 0.05). Inter-ventricular, longitudinal and radial intra-ventricular dyssynchrony also reduced significantly (all P < 0.05). Compared with DCM group, there was no significant difference in LV response rate (33.3 vs. 60.0 %, P = 0.092), improvement of LV function and dyssynchrony index (all P < 0.05). In conclusion, CRT improved heart function, morphology and mechanical dyssynchrony in LVNC patients.