Key result
Longer QLV delay is linked to a ~59% higher clinical CRT response rate.
Why the study?
A considerable proportion of patients does not respond to cardiac resynchronization therapy, and the clinical relevance of left ventricular electrode local electrogram delay (QLV) for predicting response was investigated.
Does a longer local electrogram delay (QLV) from the left ventricular lead at implant predict improved response to cardiac resynchronization therapy in patients with heart failure and LBBB or IVCD?
Cohort (n=161)
No
Does a longer local electrogram delay (QLV) from the left ventricular lead at implant predict improved response to cardiac resynchronization therapy in patients with heart failure and LBBB or IVCD?
Absolute Event Rate: 92% vs 58%
p-value: p=<0.0001
A longer QLV interval at the time of CRT implantation is a strong independent predictor of beneficial clinical response, LV reverse remodeling, and NT-proBNP reduction at 1 year.
May support QLV assessment to predict CRT response; leaves open whether QLV-guided lead placement improves outcomes.
BACKGROUND: Considerable proportion of patients does not respond to the cardiac resynchronization therapy (CRT). This study investigated clinical relevance of left ventricular electrode local electrogram delay from the beginning of QRS (QLV). We hypothesized that longer QLV indicating more optimal lead placement in the late activated regions is associated with the higher probability of positive CRT response. METHODS: We conducted a retrospective, single-centre analysis of 161 consecutive patients with heart failure and LBBB or nonspecific intraventricular conduction delay (IVCD) treated with CRT. We routinely intend to implant the LV lead in a region with long QLV. Clinical response to CRT, left ventricular (LV) reverse remodelling (i.e. decrease in LV end-systolic diameter - LVESD ≥10%) and reduction in plasma level of NT-proBNP >30% at 12-month post-implant were the study endpoints. We analyzed association between pre-implant variables and the study endpoints. RESULTS: Clinical CRT response rate reached 58%, 84% and 92% in the lowest (≤105 ms), middle (106-130 ms) and the highest (>130 ms) QLV tertile (p < 0.0001), respectively. Longer QRS duration (p = 0.002), smaller LVESD and a non-ischemic cardiomyopathy (both p = 0.02) were also univariately associated with positive clinical CRT response. In a multivariate analysis, QLV remained the strongest predictor of clinical CRT response (p < 0.00001), followed by LVESD (p = 0.01) and etiology of LV dysfunction (p = 0.04). Comparable predictive power of QLV for LV reverse remodelling and NT-proBNP response rates was observed. CONCLUSION: LV lead position assessed by duration of the QLV interval was found the strongest independent predictor of beneficial clinical response to CRT.
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Polášek et al. (2012) conducted a cohort in Heart failure with LBBB or nonspecific intraventricular conduction delay (n=161). Longer left ventricular electrode local electrogram delay (QLV) vs. Shorter QLV (≤105 ms) was evaluated on Positive clinical response to CRT at 12 months (improvement by ≥1 NYHA class and/or LVESD reduction ≥10%) (p=<0.0001). A longer left ventricular electrode local electrogram delay (QLV >130 ms) was associated with a 92% clinical response rate to cardiac resynchronization therapy compared to 58% for QLV ≤105 ms.
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