Electrocardiographic remodeling in patients paced for heart failure

doi:10.1016/S0002-9149(00)01347-3

The American Journal of Cardiology

Volume 86, Issue 9, Supplement 1, 2 November 2000, Pages K152-K156

https://doi.org/10.1016/S0002-9149(00)01347-3 Get rights and content

Abstract

Congestive heart failure due to advanced coronary artery disease or dilated cardiomyopathy is often associated with intraventricular conduction delays. Electrical resynchronization is an evolving method to improve clinical and functional status. To evaluate whether pacing-induced changes in the electrocardiogram are related to hemodynamic changes, we analyzed electrocardiograms of patients enrolled in the Pacing Therapies in Congestive Heart Failure trial. The study population consisted of 42 patients, New York Heart Association functional class III–IV with a baseline QRS complex of 175 ± 32 msec and a PR interval of 196 ± 33 msec. The mean left ventricular ejection fraction was 0.23. Using high-resolution computer scans, we measured QRS duration of intrinsic and paced electrocardiographs at different times during the study. Results of the electrocardiographic measurements were correlated with functional results. During the crossover period, 34 episodes of biventricular pacing, 27 episodes of left ventricular pacing, and 5 episodes of right ventricular pacing occurred, each at an individual optimized atrioventricular (AV) delay. The only significant difference was that right ventricular pacing increased the QRS width by 40 msec as compared with baseline or biventricular pacing. Functional benefit, as indicated by relative increase of peak oxygen uptake (VO₂) compared with baseline, was significantly correlated with shortening of paced QRS width (correlation coefficient, r = 0.55; p <0.05). After 12-month follow-up of 28 patients, we saw a slight, nonsignificant decrease of intrinsic QRS width. With regard to the underlying disease, intrinsic QRS width at baseline and at 12 months was also not significantly different between patients with coronary artery disease and dilated cardiomyopathy. This study found that right ventricular pacing causes an increase in QRS duration in patients with left bundle-branch block, whereas in left ventricular and biventricular pacing, QRS width remains unchanged. Shortening of QRS width is correlated with a pronounced relative increase of peak VO₂, and thus may become a noninvasive marker of clinical efficacy. There is no evidence of remodeling of the intrinsic electrocardiogram after 12 months of pacing.

Section snippets

Purpose of the study

On the basis of electrocardiographic alteration, we analyzed the influence of electrocardiographic remodeling on the clinical course of patients followed-up during the Pacing Therapies of Congestive Heart Failure (PATH-CHF) study. In addition, we analyzed the course of intrinsic AV and intraventricular conduction delays in the native electrocardiogram after 12 months of successful univentricular or biventricular pacing therapy, in comparison with the initial electrocardiogram. The PATH-CHF5

Results

Morphologic analysis of the intrinsic electrocardiogram before implantation revealed left bundle-branch block with discordance (superior axis) in 23 patients, left bundle-branch block with concordance in 16 patients, 1 patient with right bundle-branch block with left anterior hemiblock, and 2 patients with right bundle-branch block with left posterior hemiblock. Mean QRS duration was 175 ± 32 msec (range, 123–268 msec) and mean P-R interval 196 ± 33 msec (124–280 msec). During the crossover

Discussion

The present results prove that the predominant intraventricular conduction disorder in patients with congestive heart failure of ischemic or nonischemic origin is the discordant or concordant left bundle- branch block. Atrial–right-ventricular pacing leads to significant prolongation of the QRS complex by the asynchronous electrical excitation of both ventricles independent of the present AV interval. However, if atriouniventricular pacing is performed at the free wall of the ventricle with the

Acknowledgements

The authors thank the investigators of the participating centers of the University RWTH Aachen, the University GHS Essen, the Westfälische Wilhems University Münster, Germany, the Skejby Sygehus, Aarhus, Denmark, for the electrocardiographic recordings and acknowledge the generous support by Thierry Pochet and Annette Dölger, Guidant, in the discussion and evaluation of the data, and Astrid Kohlstädt-Klapper for preparing the manuscript and reproducing the figures.

References (7)

H Xiao et al.
Natural history of abnormal conduction and its relation to prognosis in patients with dilated cardiomyopathy
Int J Cardiol
(1996)
L.A Saxon et al.
Acute effects of intraoperative multisite ventricular pacing on left ventricular function and activation/contraction sequence in patients with depressed ventricular function
J Cardivasc Electrophysiol
(1998)
D.A Kass et al.
Improved left ventricular mechanics from acute VDD pacing in patients with dilated cardiomyopathy and ventricular conduction delay
Circulation
(1999)

There are more references available in the full text version of this article.

Cited by (34)

Time Course of Electrical Remodeling of Native Conduction After Cardiac Resynchronization Therapy and Its Impact on Clinical Outcome
2017, Journal of Cardiac Failure
Citation Excerpt :
Data on whether restitution of native conduction system is accompanied by recovery of LV remodeling are inconsistent. Early studies reported no change in native QRS duration after CRT.3,10 Coinciding with our results, recent publications demonstrated significant native QRS narrowing after CRT associated with LV mechanical remodeling.4,5,11
Cardiac resynchronization therapy (CRT) induces structural and electrical remodeling (ER) in heart failure (HF) patients. Our aim was to assess time course of ER of native conduction and mechanical remodeling after CRT and impact of CRT-induced ER on clinical outcome.
We prospectively included 62 patients (aged 66 ± 10 years). Echocardiographic and ECG parameters were measured at baseline and 1, 3, 6, 9, and 12 months after implantation. Biventricular pacing was temporary inhibited during each follow-up to record intrinsic ECG. ER was defined as a decrease in native pre-implantation QRS duration ≥10 ms. During follow-up HF hospitalizations, cardiovascular death and transplantation (combined end point) were recorded. There were significant changes in intrinsic ECG parameters during follow-up; the narrowing of QRS duration was already observed after 1 month (median 185 ms [interquartile range (IQR) 175–194] vs 180 ms [170–194]; P < .001). Left ventricular (LV) volumes decreased only after 3 months of CRT (median end-systolic volume 167 mL [137–206] vs 140 mL [112–196]; P < .001). Only patients with ER (n = 24) exhibited significant mechanical remodeling and showed superior survival free from the combined end point compared with patients without ER (log-rank P = .028).
Electrical remodeling of native conduction precedes detectable left ventricular structural changes after CRT. ER of native conduction is associated with better clinical outcome following CRT.
Native Electrocardiographic QRS Duration after Cardiac Resynchronization Therapy: The Impact on Clinical Outcomes and Prognosis
2016, Journal of Cardiac Failure
Citation Excerpt :
CRT has been primarily accepted as an electrical therapy that aims to restore the synchronicity of the conduction system in the failing heart.18 The evidence arising from RV-pacing studies19 supports that deterioration of intraventricular conduction by inducing iatrogenic LBBB further affects LV systolic dysfunction and can be reversed with the use of biventricular pacing.20 In addition, complete restoration of the electrical remodeling in a patient with LBBB resulted in superresponse to CRT, as shown by Dizon et al,21 suggesting that reversal of electrical remodeling is the main target of biventricular pacing in heart failure.
We investigated whether reversed electrical remodeling (RER), defined as narrowing of the native electrocardiographic QRS duration after cardiac resynchronization therapy (CRT), might predict prognosis and improvement in echocardiographic outcomes.
A total of 110 CRT recipients were retrospectively analyzed for the end points of death and hospitalization during 18 ± 3 months. Native QRS durations were recorded at baseline and 6 months after CRT (when pacing was switched off to obtain an electrocardiogram) to determine RER. CRT response and mitral regurgitation (MR) improvement were defined as ≥15% reduction in left ventricular end-systolic volume and absolute reduction in regurgitant volume (RegV) at 6 months, respectively. Overall, 48 patients (44%) had RER, which was associated with functional improvement (77% vs 34%; P < .001) and CRT response (81% vs 52%; P < .001) compared with those without RER. The change in the intrinsic QRS duration correlated with the reduction in RegV (r = 0.51; P < .001) and in tenting area (r = 0.34; P < .001). RER was a predictor of MR improvement (P = .023), survival (P = .043), and event-free survival (P = .028) according to multivariate analyses.
Narrowing of the intrinsic QRS duration is associated with functional and echocardiographic CRT response, reduction in MR, and favorable prognosis after CRT.
Electrocardiographic alterations after chronic right ventricular apical pacing in patients with sinus node dysfunction
2009, Journal of Electrocardiology
Citation Excerpt :
3) An elderly age at implant, chronic RVA pacing, and the presence of CAD were independent predictors for the prolongation of QRS duration. Most of the previous studies regarding electrical remodeling have focused on effects during RVA pacing, as opposed to effects on the native conduction system.9,13-15 The width of the paced QRS has been shown to be negatively correlated with left ventricular (LV) function, and prolonged paced QRS duration was a predictor of the development of heart failure in patients with RVA pacing for SND.16,17
The purpose of this study is to investigate the potential to induce electrical remodeling by chronic right ventricular apical (RVA) in patients with sinus node dysfunction.
Ninety-two patients with sinus node dysfunction who underwent initial pacemaker implantation were included in the study. During routine clinic visits, electrocardiograms and echocardiograms were recorded. Forty-five patients were also studied as controls.
During a mean follow-up time of 3.3 ± 0.5 years, the intrinsic QRS duration increased from 87 ± 9 milliseconds before device implantation to 94 ± 10 milliseconds (P < .001). The left ventricular end-diastolic diameter increased from 46 ± 3 to 50 ± 4 mm (P < .001), and the left ventricular ejection fraction decreased from 63% ± 4% to 57% ± 5% (P < .001). Logistic regression analysis revealed that elderly age at the time of pacemaker implantation (odds ratio [OR], 3.41; 95% confidence interval [CI], 1.07-10.90; P = .04), RVA pacing (OR, 3.91; 95% CI, 1.10-13.89; P = .03), and coronary artery disease (OR, 7.33; 95% CI, 1.09-50.29; P = .04) were independent predictors of the prolongation of intrinsic QRS duration.
The present study indicated that chronic RVA pacing may lead to a prolongation of intrinsic QRS duration, which could be independently predicted by elderly age, chronic RVA pacing, and the presence of coronary artery disease.
Temporal Variation in Optimal Atrioventricular and Interventricular Delay During Cardiac Resynchronization Therapy
2006, Journal of Cardiac Failure
Citation Excerpt :
Furthermore, previous reports suggest the lack of CRT effect on electrical remodeling. QRS duration of intrinsic electrocardiographs remained unchanged in 42 patients with HF after 12 months of pacing at an individual optimized AVd.21 Improvement in systolic function and mechanical resynchronization after biventricular pacing occurs without electrical synchrony.22
Tailored atrioventricular delay (AVd) and interventricular delay (VVd) combination improves hemodynamics in patients treated with cardiac resynchronization therapy (CRT). Whether tailored AVd-VVd combination changes over time is not known.
Twenty-two patients (18 M, aged 69.9 ± 12.5 years, New York Heart Association class III, QRS ≥ 130 ms, ejection fraction 29.6 ± 8.8%) were implanted with a biventricular device with programmable VVd. Myocardial performance index (MPI) was evaluated during pacing at different VVds and AVds at baseline and after 6 and 12 months. The optimal AVd-VVd combination was identified by the minimum MPI. After optimization, the appropriate AVd-VVd combination was programmed in each patient. MPI at 6-month follow-up after optimization was significantly higher compared with baseline (.79 ± .21 vs. .59 ± .15, P < .05). Re-optimization of AVd-VVd combination was required after 6 months in 21 of 22 (95%) patients. Re-optimization significantly reduced MPI compared with the value prior to re-optimization (.56 ± .15 vs. .79 ± .21, P < .05). The MPI remained unchanged at 12-month compared with 6-month follow-up (.59 ± .19 vs. .56 ±.15, P = NS). Clinical symptoms and reverse left ventricular remodeling were sustained at 6-month and 12-month follow-up.
Optimal AVd and VVd combination changes over time in patients with heart failure. Sustained improvement in clinical symptoms and reverse left ventricular remodeling after CRT are not temporally associated with improvement in MPI.
Electrocardiographic remodeling during cardiac resynchronization therapy
2006, International Journal of Cardiology
More information is required on the relationship between electrical and structural reverse remodeling in patients treated with cardiac resynchronization theraphy.
QRS and JT intervals were investigated during different pacing modes before and 3 months after implantation of a device for biventricular (BiV) pacing in 20 patients with severe drug-refractory heart failure (with left ventricular ejection fraction < 40% and QRS > 120 ms); structural remodeling was evaluated by echocardiography.
QRS interval was significantly shortened by BiV pacing both acutely (p = 0.002) and at 3 months (p = 0.007). No significant change was found in the JT interval. The extent of QRS shortening obtained by BiV pacing showed moderate correlations with the reduction of end-systolic and end-diastolic volumes (r = 0.53, p = 0.016 and r = 0.45, p = 0.045, respectively) as well as with increase of left ventricular ejection fraction (r = 0.49, p = 0.028) at 3 months. The widening of QRS observed during right ventricular (RV) pacing was greater after 3 months of BiV pacing (with respect to acute assessments), suggesting accentuation of pacing-induced electrical dyssynchrony after a period of pacing-induced resynchronization.
The extent of QRS shortening induced by BiV pacing appears to correlate with the reverse structural remodeling (in terms of reduction in end-systolic volume). The acute changes and the remodeling process occurring at mid-term in the overall population of CRT-treated patients do not appear to involve the JT interval. A period of pacing-induced resynchronization appears to accentuate the potential for RV pacing-driven electrical dyssynchrony.
Cardiac resynchronization therapy: Caveat medicus!
2004, Journal of the American College of Cardiology
The device era in heart failure has been heralded by successes in the realm of pacemakers, implantable defibrillators, and ventricular assist devices. In particular, the concept of cardiac resynchronization therapy, which seeks to optimize ventricular contractility by decreasing areas of focal dyssynchrony, is gaining wide acceptance. Recent trials of cardiac resynchronization therapy have suggested that this treatment modality yields benefits that are reflected in improved functional capacity, reversal of ventricular modeling, and decreased hospitalizations. Cardiac resynchronization device therapy exerts a substantial placebo effect, with evidence of improved functional capacity and quality-of-life parameters in almost half of those in the control group, probably as a result of device implantation. Furthermore, analysis of the different trials suggests heterogeneity of response (differences in magnitude of observed benefit between trials presumably enrolling similar heart-failure populations) and a large non-responder rate (no improvement in functional capacity and well-being). The appropriate approach to resynchronization must include much more than simple characteristics of device implantation. We must detect the presence and precise location of mechanical dyssynchrony and be able to find the technical location and place the pacing leads in the appropriate position. Finally, we must be able to show evidence for sustained improvement in ventricular dyssynchrony. Thus, the current approach to resynchronization represents a “best guess” approach to achieving resynchronization by observation of surrogate responses. Continued investigation to determine optimal approaches for achieving a beneficial clinical response is essential to ensure that cardiac resynchronization therapy is offered to those most likely to benefit.

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View full text

Electrocardiographic remodeling in patients paced for heart failure

Abstract

Section snippets

Purpose of the study

Results

Discussion

Acknowledgements

Int J Cardiol

Acute effects of intraoperative multisite ventricular pacing on left ventricular function and activation/contraction sequence in patients with depressed ventricular function

J Cardivasc Electrophysiol

Improved left ventricular mechanics from acute VDD pacing in patients with dilated cardiomyopathy and ventricular conduction delay

Circulation