Pacing In Heart Failure Research Articles

Atrioventricular Optimized Direct His Bundle Pacing Improves Acute Hemodynamic Function in Patients With Heart Failure and PR Interval Prolongation Without Left Bundle Branch Block

ObjectivesThe purpose of this study was to investigate whether heart failure patients with narrow QRS duration (or right bundle branch block) but with long PR interval gain acute hemodynamic benefit from atrioventricular (AV) optimization. We tested this with biventricular pacing and (to deliver pure AV shortening) direct His bundle pacing. BackgroundBenefits of pacing for heart failure have previously been indicated by acute hemodynamic studies and verified in outcome studies. A new target for pacing in heart failure may be PR interval prolongation, which is associated with 58% higher mortality regardless of QRS duration. MethodsWe enrolled 16 consecutive patients with systolic heart failure, PR interval prolongation (mean, 254 ± 62 ms) and narrow QRS duration (n = 13; mean QRS duration: 119 ± 17 ms) or right bundle branch block (n = 3; mean, QRS duration: 156 ± 18 ms). We successfully delivered temporary direct His bundle pacing in 14 patients and temporary biventricular pacing in 14 participants. We performed AV optimization using invasive systolic blood pressure obtaining parabolic responses (mean R2: 0.90 for His, and 0.85 for biventricular pacing). ResultsThe mean increment in systolic BP compared with intrinsic ventricular conduction was 4.1 mm Hg (95% confidence interval [CI]: +1.9 to +6.2 mm Hg for His and 4.3 mm Hg [95% CI: +2.0 to +6.5 mm Hg] for biventricular pacing. QRS duration lengthened with biventricular pacing (change = +22 ms [95% CI: +18 to +25 ms]) but not with His pacing (change = +0.5 ms [95% CI: −2.6 to +3.6 ms). ConclusionsAV-optimized pacing improves acute hemodynamic function in patients with heart failure and long PR interval without left bundle branch block. That it can be achieved by single-site His pacing shows that its mechanism is AV shortening. The improvement is ∼60% of the effect size previously reported for biventricular pacing in left bundle branch block. Randomized, blinded trials are warranted to test for long-term beneficial effects.

59 * Age-adjusted Charlson score: a novel clinical predictor of one-year mortality after biventricular pacing for heart failure

Introduction: Cardiac resynchronisation therapy (CRT) has been reported to significantly reduce one–year mortality from 12.6 percent to 9.7 percent when compared with optimal medical therpay for patients with heart failure. We aimed to establish whether improved one-year mortality rates continue to be observed in real world clinical practice. Methods: We performed post-hoc analysis of all patients implanted with new CRT devices at the Manchester Heart Centre between 04/01/2010 to 15/11/2011. Baseline characteristics were collected prospectively. Patient mortality at one-year was recorded using contemporaneous electronic records. Results: 228 patients received new CRT devices during the study period. Co-morbidities included diabetes mellitus (21%), ischaemic heart disease (65%) and chronic kidney disease (14%). 183 patients (86%) were in NYHA class III and 30 (13%) NYHA class IV. 42% of patients received a CRT-P device, the remainder (58%) received CRT-D. 29/228 patients (13%) died within 1-year of implantation (10% in CRT-P and 14% of CRT-D recipients). Age-adjusted Charlson score was significantly higher in patients who died within 1 year than those who survived (5.66 vs. 4.25; p<0.0001). Presence of ischaemic heart disease and chronic kidney disease also carried significantly higher 1-year mortality. Conclusion: One-year mortality after CRT remains significant. Age adjusted Charlson score was significantly higher in patients who died at one year compared to those who survived. Age-adjusted Charlson score predicts higher mortality risk in patients under consideration for CRT and should be used routinely when evaluating patients for device implant to identify those at greatest risk of mortality.

Erratum to ‘Heart failure highlights in 2012–2013’ [Eur J Heart Fail 2014;16:122

Two additional references need to be added to this review paper. 100. Rogers DP, Lambiase PD, Lowe MD, Chow AW. A randomized double-blind crossover trial of triventricular versus biventricular pacing in heart failure. Eur J Heart Fail 2012;14:495–505. 101. Maass AH, van Veldhuisen DJ. Device therapy in patients with heart failure and preserved ejection fraction (HFPEF): a new frontier? Eur J Heart Fail 2010;12:527–529. On page 128, the following text with citations 68 and 8 must read as 100 and 101 as given further below: To place three ventricular leads, either two LV or two right ventricular (RV) leads, seems to be better than conventional CRT,68 whereas the position of the RV lead per se (apical or outflow tract) seems to be insignificant.85 Device therapy for HFPEF seems a potentially attractive novel target.8 Replacement text: To place three ventricular leads, either two LV or two right ventricular (RV) leads, seems to be better than conventional CRT,100 whereas the position of the RV lead per se (apical or outflow tract) seems to be insignificant.85 Device therapy for HFPEF seems a potentially attractive novel target.101 In addition one acronym in Table 1 should be corrected. On page 123, the following acronym SHOCK2, should be read as IABP-SHOCK 2.

Biventricular pacing in heart failure: right is not wrong!

Biventricular pacing in heart failure: right is not wrong!

Electrophysiological characteristics of complex fractionated electrograms and high frequency activity in atrial fibrillation

It is unclear whether atrial substrate with complex fractionated electrograms (CFAEs) is related to arrhythmogenesis. This study aimed to investigate the electrophysiology in CFAE and high dominant frequency (DF) areas. Atrial fibrillation (AF) was induced by rapid atrial pacing in heart failure (HF) rabbits (4 weeks after coronary artery ligation). Real-time substrate mapping, multielectrode array, and monophasic action potential recordings were used to study areas of CFAE and DF. Conventional microelectrode and western blot were used to record the action potentials (APs) and protein expression in isolated tissue preparations. CFAE site with high DF had the most depolarized resting membrane potential, highest incidence of early and delayed afterdepolarizations, and steepest maxima slope of 90% of AP duration (APD90) restitution curve (RC) compared to CFAE site with low DF or non-CFAE sites. CFAE site with high DF exhibited the slowest conduction velocity and shortest wavelength than the other areas. Upregulation of the Na(+)-Ca(2+) exchanger (NCX), apamin-sensitive small-conductance Ca(2+)-activated K(+) channel type 2 (SK2) and sarcoplasmic reticulum Ca(2+)-ATPase, and downregulation of the Kir2.1 were found at CFAE site with high DF compared to that observed in the 3 other areas. Inhibition of the NCX and SK channels prolonged the APD90, flattened the maximum slope of RC, and suppressed AF. CFAE site with high DF had an arrhythmogenic property differing significantly from the other areas of LA in an HF rabbit model, which may contribute to the genesis of AF.

Atrial Support Pacing in Heart Failure: Results from the Multicenter PEGASUS CRT Trial

Cardiac resynchronization therapy (CRT) efficacy trials to date used atrial-synchronous biventricular pacing wherein there is no or minimal atrial pacing. However, bradycardia and chronotropic incompetence are common in this patient population. This trial was designed to evaluate the effect of atrial support pacing among heart failure patients receiving a CRT defibrillator. PEGASUS CRT was a multicenter, 3-arm, randomized study. At 6 weeks, patients were randomized to DDD mode at a lower rate of 40 bpm (DDD-40; control arm), or one of the following 2 treatment arms: DDD-70, or DDDR-40. The primary endpoint was a clinical composite endpoint that included all-cause mortality, heart failure events, NYHA functional class, and patient global self-assessment. Subjects were classified as improved, unchanged, or worsened at 12 months. There were 1,433 patients randomized, of whom 66% were male, mean age was 67 ± 11 years, and mean left ventricular ejection fraction was 23 ± 7%. The average follow-up time was 10.5 ± 3.5 months and 1,309 patients contributed to the primary endpoint. No significant differences were observed in the composite endpoint between either of the 2 treatment arms compared to the control arm (P>0.05 for both comparisons). Additionally, there were no differences among the groups in mortality or heart failure events. In advanced heart failure patients treated with CRT, atrial support pacing did not improve clinical outcomes compared to atrial tracking. However, atrial pacing did not adversely affect mortality or heart failure events.

Optimizing Electrode Placement for Hemodynamic Benefit in Cardiac Resynchronization Therapy

Research is needed to explore the relative benefits of alternative electrode placements in biventricular and left ventricular (LV) pacing for heart failure with left bundle branch block (LBBB). A fast computational model of the left ventricle, running on an ordinary laptop computer, was created to simulate the spread of electrical activation over the myocardial surface, together with the resulting electrocardiogram, segmental wall motion, stroke volume, and ejection fraction in the presence of varying degrees of mitral regurgitation. Arbitrary zones of scar and blocked electrical conduction could be modeled. Simulations showed there are both sweet spots and poor spots for LV electrode placement, sometimes separated by only a few centimeters. In heart failure with LBBB, pacing at poor spots can produce little benefit or even reduce pumping effectiveness. Pacing at sweet spots can produce up to 35% improvement in ejection fraction. Relatively larger benefit occurs in dilated hearts, in keeping with the greater disparity between early and late activated muscle. Sweet spots are typically located on the basal to midlevel, inferolateral wall. Poor spots are located on or near the interventricular septum. Anteroapical scar with conduction block causes little shift in locations for optimal pacing. Hearts with increased passive ventricular compliance and absence of preejection mitral regurgitation exhibit greater therapeutic gain. The durations and wave shapes of QRS complexes in the electrocardiogram can help predict optimum electrode placement in real time. Differences between poor responders and hyperresponders to cardiac resynchronization therapy can be understood in terms of basic anatomy, physiology, and pathophysiology. Computational modeling suggests general strategies for optimal electrode placement. In a given patient heart size, regional pathology and regional dynamics allow individual pretreatment planning to target optimal electrode placement.

Meta‐analysis of randomized controlled trials evaluating left ventricular vs. biventricular pacing in heart failure: effect on all‐cause mortality and hospitalizations

Randomized controlled trials (RCTs) showed that biventricular (BiV) pacing reduces heart failure (HF) hospitalizations and mortality in patients with New York Heart Association (NYHA) class III-IV HF, left ventricular (LV) dysfunction, and wide QRS. We performed a systematic review and meta-analysis of the RCTs comparing LV-only vs. biventricular (BiV) pacing in candidates for cardiac resynchronization therapy (CRT). The systematic review selected five RCTs (out of 1888 analysed reports) with a cumulative number of 372 patients randomized to BiV pacing and 258 to LV-only pacing. The meta-analysis shows that BiV pacing is not superior to LV-only pacing and that these two pacing modalities do not differ with regard to death or heart transplantation [LV-only vs. BiV pacing odds ratio (OR) 1.24, 95% confidence interval (CI) 0.57-2.70 with the fixed effect model, OR 1.25, 95% CI 0.48-3.24 with the random effect model]. Specific data on hospitalizations were available only in two RCTs with a cumulative number of 127 patients randomized to BiV and 123 to LV-only pacing. The meta-analysis shows that BiV pacing is not superior to LV-only pacing and that these two pacing modalities do not differ with regard to this outcome (LV-only vs. BiV pacing OR 0.86, 95% CI 0.49-1.50 with the fixed effect model, OR 0.86, 95% CI 0.49-1.50 with the random effect model). Biventricular pacing is not superior to LV-only pacing, and these two pacing modalities appear to achieve similar efficacy in candidates for CRT for moderate to severe HF, in terms of all-cause mortality and hospitalizations during follow-up.

Relation of Dosing of the Renin–Angiotensin System Inhibitors After Cardiac Resynchronization Therapy to Long-Term Prognosis

Dosing of angiotensin-converting enzyme (ACE) inhibitors and angiotensin receptor blockers (ARBs) in patients with heart failure (HF) treated with cardiac resynchronization therapy (CRT) may affect long-term outcomes. Retrospective data were collected at baseline and follow-up for consecutive patients who had CRT implanted and attended the institutional specialist HF pacing clinic. The study end point was death from any cause or hospitalization for worsening HF 24 months after implantation. Ninety-one patients (72 men, 68 ± 12 years old) with decreased left ventricular ejection fraction (24 ± 6%) were included. At baseline 85 patients (93%) were on ACE inhibitors/ARBs. At 6 months 3 patients had died and 86 of 88 (98%) were on ACE inhibitors/ARBs. Doses were uptitrated from 55 ± 35% of target dose (TD) at baseline to 62 ± 31% TD at month 6 (p = 0.018), whereas blood pressure was unchanged. Patients treated with <50% TD of ACE inhibitors/ARBs (n = 20) at month 6 had worse 24-month event-free survival than those on 50% to 99% TD (n = 38, p = 0.011, log-rank test) or ≥100% TD (n = 30, p = 0.007, log-rank test). Failure to achieve a dose ≥50% TD of ACE inhibitors/ARBs at 6 months after CRT implantation was an independent predictor of all-cause mortality or hospitalization (hazard ratio 3.99, 95% confidence interval 1.66 to 9.62, p = 0.002) after adjustment for potential confounders including age, estimated glomerular filtration rate, diabetes and New York Heart Association class. In conclusion optimal dosing of ACE inhibitors/ARBs is an independent predictor of prognosis in patients with HF treated with CRT and it can be achieved by a structured follow-up within a specialized HF pacing clinic.

Cell-to-cell variability in troponin I phosphorylation in a porcine model of pacing-induced heart failure

We tested the hypothesis that myocardial contractile protein phosphorylation and the Ca2+ sensitivity of force production are dysregulated in a porcine model of pacing-induced heart failure (HF). The level of protein kinase A (PKA)-dependent cardiac troponin I (TnI) phosphorylation was lower in the myocardium surrounding the pacing electrode (pacing site) of the failing left ventricle (LV) than in the controls. Immunohistochemical assays of the LV pacing site pointed to isolated clusters of cardiomyocytes exhibiting a reduced level of phosphorylated TnI. Flow cytometry on isolated and permeabilized cardiomyocytes revealed a significantly larger cell-to-cell variation in the level of TnI phosphorylation of the LV pacing site than in the opposite region in HF or in either region in the controls: the interquartile range (IQR) on the distribution histogram of relative TnI phosphorylation was wider at the pacing site (IQR = 0.53) than that at the remote site of HF (IQR = 0.42; P = 0.0047) or that of the free wall of the control animals (IQR = 0.36; P = 0.0093). Additionally, the Ca2+ sensitivities of isometric force production were higher and appeared to be more variable in single permeabilized cardiomyocytes from the HF pacing site than in the healthy myocardium. In conclusion, the level of PKA-dependent TnI phosphorylation and the Ca2+ sensitivity of force production exhibited a high cell-to-cell variability at the LV pacing site, possibly explaining the abnormalities of the regional myocardial contractile function in a porcine model of pacing-induced HF.Electronic supplementary materialThe online version of this article (doi:10.1007/s00395-012-0244-x) contains supplementary material, which is available to authorized users.

Diastolic relaxation and compliance reserve during dynamic exercise in heart failure with preserved ejection fraction

BackgroundRecent studies have examined haemodynamic changes with stressors such as isometric handgrip and rapid atrial pacing in heart failure with preserved ejection fraction (HFpEF), but little is known regarding left...

Intramural dyssynchrony and response to cardiac resynchronization therapy in patients with and without previous right ventricular pacing

Right ventricular (RV) pacing is an iatrogenic cause of heart failure (HF) that has not been well studied. We assessed whether HF patients paced from the right ventricle (RVp) adversely remodel and respond to cardiac resynchronization therapy (CRT) in a similar way to HF patients without right ventricular pacing (nRVp). Echocardiograms were performed before and ∼5 months after CRT in 31 RVp and 49 nRVp HF patients. Longitudinal intraventricular dyssynchrony using tissue Doppler imaging (TDI) was calculated as the standard deviation of time to peak systolic displacement by tissue tracking (SD-TT) of 12 segments. Longitudinal dyssynchrony within a wall (intramural dyssynchrony) was assessed by two methods: quantifying the number of segments with initial abnormal apical displacement (IMD score) and using a cross-correlation synchrony index (CCSI). Despite similar ejection fractions (EFs) of 28% prior to CRT, left ventricular end-diastolic volume was significantly smaller (143±54 vs. 183±62, P=0.004) in RVp. The standard deviation of time to peak systolic displacement by tissue tracking (83.4±34.9 vs. 67.9±26.6, P=0.03) and IMD score (3.1±1.8 vs. 1.3±1.7, P<0.001) were greater in RVp. Cardiac resynchronization therapy significantly improved EF and volumes in both groups. Ejection fraction increased more in RVp (12.8±9.2% vs. 7.4±7.6%, P=0.007). Intraventricular dyssynchrony and both measures of intramural septal dyssynchrony improved to a greater extent post-CRT in RVp. Right ventricular pacing patients differ from nRVp HF patients in that they have smaller ventricles and greater intraventricular and intramural septal dyssynchrony. Right ventricular pacing HF patients respond better to CRT with greater improvements in EF, and intraventricular and intramural septal dyssynchrony.

Positive hemodynamic and clinical response to tri–left ventricular pacing in a nonresponder to traditional cardiac resynchronization therapy

Multisite left ventricular (LV) pacing is technically challenging, but may result in clinical improvement in patients who do not derive hemodynamic benefit from traditional biventricular pacing. 1 Leclercq C. Gadler F. Kranig W. et al. A randomized comparison of triple-site versus dual-site ventricular stimulation in patients with congestive heart failure TRIP-HF (Triple Resynchronization In Paced Heart Failure Patients) Study Group. J Am Coll Cardiol. 2008; 51: 1455-1462 Abstract Full Text Full Text PDF PubMed Scopus (181) Google Scholar , 2 Bordachar P. Alonso C. Anselme F. et al. Addition of a second LV pacing site in CRT nonresponders rationale and design of the multicenter randomized V(3) trial. J Card Fail. 2010; 16: 709-713 Abstract Full Text Full Text PDF PubMed Scopus (27) Google Scholar We present the case of a patient who had an implantable cardioverter-defibrillator (ICD) implanted, with 3 epicardial LV leads, in addition to an epicardially placed ICD lead.

The influence of puerarin injection combined with irbesartan on atrial fibrillation and r induced by ventricular fibrous ventricular rapid pacing heart failure in dogs

Objective To observe the combined effects of puerarin injection and irbesartan on congestive heartfailure(CHF) in dogs with ventricula fibrous ventricular rapid pacing heart failure.Methods 21 healthy mongrel dogs were randomly divided into normal control group,CI-IF model group and the TMP treated group.CHF was established by right ventricular pacing model of canine.Butst was used to evoke atrial fibrillation (atrial fibrill;tripn,LVEF).Echocardiography was used to detect left ventricular ejection fraction in dogs (Left ventricular ejection fraction,LVEF).Mallory's three-color staining was used to detect the degree of atrial fiber.The level of plasma angiotensin 1,aldosterone concentration,m-type forelimb of the original N-terminal peptide (amino-terllllrlal1 ～ eptldcoftype Ⅲ procollagen,P Ⅲ NP),laminin (1 alTlmln,IN),and hyaluronic acid (hyaltlronlcacid,HA)was detected with radioimmunoassay.Results The LVEF of CHF model group decreased significantly compared with the control group(P ＜0.01).AF incidence ,the incidence of persistent AF and AF duration were significantly increased when compared with the control group(P ＜ 0.01).Left atrial fibrosis were also significantly increased in CHF model group than normal control group (P ＜ 0.01).AF duration was positively correlated with the degree of left atrial fiber (r = 0.84,P = 0.018).plasma angiotensin Ⅱ ,aldosterone,and serurn P Ⅲ NP,HA levels were significantly higher than normal control group(P ＜0.05 or P ＜0.01).There was no statistical difference in LN.Plasma angiotensin Ⅱ and aldosterone levels showed a close positive correlation(r =0.759 ,P =0.182).There is significant improvement in LVEF in treatment group when compared with model group(P ＜ 0.05).The incidence of persistent AF was significantly lower in treated group when compared with CHF model(P ＜ 0.05).The left atrial fibrosis was significantly reduced in treated group when compared with CHF(P ＜ 0.01).Conclusion Puerarin injection combined with irbesartan can reduce II-IF degree of atrial fiber,which may be one of the mechanisms of the reduction of the incidence and duration of CHF and AF. Key words: Puerarin injection; Irbesartan; Joint; Heart failure; Congestive; Atrial fibrillation

LV-Only and LV-First Pacing Demonstrate Greater Improvements in Acute Hemodynamics Than Synchronous BiV Pacing in Heart Failure With Preserved Ejection Fraction

Background: Heart failure with a preserved ejection fraction (HFpEF) remains poorly understood with few options for treatment. Recent evidence identified regional delays in cardiac mechanical activation in HFpEF despite a narrow QRS and normal chamber size. We compared the acute effects of synchronous BiV pacing (VV0), BiV pacing with LV first (LVfirst) and LV only (LVonly) pacing on mechanical dyssynchrony and hemodynamics in HFpEF. Methods: HF patients with EF >50% and echocardiographic evidence of dyssynchrony were studied during cardiac catheterization.

RV Electrical Activation in Heart Failure During Right, Left, and Biventricular Pacing

To compare right ventricular (RV) activation during intrinsic conduction or pacing in heart failure (HF) patients. RV activation during intrinsic conduction or pacing in patients with left ventricular (LV) dysfunction is unclear but may affect the prognosis. In cardiac resynchronization therapy (CRT), timed LV pacing (CRT-LV) may be superior to biventricular pacing (CRT-BiV), and is hypothesized to be due to the merging of LV-paced and right bundle branch-mediated wavefronts, thus avoiding perturbation of RV electrical activation. Epicardial RV activation duration (RVAD) (onset to end of free wall activation) was evaluated noninvasively by electrocardiographic imaging in healthy control subjects (n = 7) and compared with that of HF patients (LV ejection fraction 23 +/- 10%, n = 14). RVAD in HF was contrasted during RV pacing, CRT-BiV, and CRT-LV at optimized AV intervals. During intrinsic conduction in HF (n = 12), the durations of QRS and precordial lead rS complexes were 158 +/- 24 and 77 +/- 17 ms, respectively, indicating delayed total ventricular depolarization but rapid initial myocardial activation. Echocardiography demonstrated no significant RV disease. RV epicardial voltage, activation patterns, and RVAD in HF did not differ from normal (RVAD 32 +/- 15 vs. 28 +/- 3 ms, respectively, p = 0.42). In HF, RV pacing generated variable areas of slow conduction and prolonged RVAD (78 +/- 33 ms, p < 0.001). RVAD remained delayed during CRT-BiV at optimized atrioventricular intervals (76 +/- 32 ms, p = 0.87). In contrast, CRT-LV reduced RVAD to 40 +/- 26 ms (p < 0.016), comparable to intrinsic conduction (p = 0.39) but not when atrioventricular conduction was poor or absent. In HF patients without RV dysfunction treated with CRT, normal RV free wall activation in intrinsic rhythm indicated normal right bundle branch-mediated depolarization. However, the RV was vulnerable to the development of activation delays during RV pacing, whether alone or with CRT-BiV. These were avoided by CRT-LV in patients with normal atrioventricular conduction.

Ventricular optimization of biventricular pacing: a systematic review

Biventricular pacing has been shown to improve the overall clinical outcomes in patients with systolic heart failure and ventricular conduction delay on electrocardiogram. As correction of ventricular dyssynchrony is the putative mechanism of benefit, biventricular pacing is also termed as cardiac resynchronization therapy. The development of separate programmability of right and left ventricular output has led to a growing number of reports on the potential benefit of optimization of cardiac resynchronization by sequential biventricular pacing with different techniques and endpoints. This systematic review summarizes the current data for the optimization of sequential (V-V delay) compared with (default) simultaneous biventricular pacing in heart failure.

Assessment of Early Changes in the Segmental Functions of the Left and the Right Ventricles After Biventricular Pacing in Heart Failure: A Study With Tissue Doppler Imaging

Tissue Doppler imaging allows assessment of systolic and diastolic regional ventricular function. The aim of this study was to assess early changes in regional systolic and diastolic functions and differences in transition time to contraction between the ventricles after cardiac resynchronization therapy. Fourteen patients were included, who underwent echocardiography before and 1 month after resynchronization. The difference between transition time to contraction of left and right ventricles decreased to 24.4 +/- 10.7 milliseconds from 65.3 +/- 18.2 milliseconds after resynchronization therapy (P = .001). There was a significant relation between the decrease in difference between transition time and increase in ejection fraction (r = 0.80, P = .002). Early or late diastolic myocardial motion increased in 7 segments of left and 2 segments of right ventricles. Systolic myocardial motion increased in 7 segments of left and in all segments of right ventricles. Resynchronization therapy improved systolic and diastolic functions in both ventricles. The difference between transition time to contraction of ventricles might be helpful in estimating optimal resynchronization.

Left Ventricular versus Biventricular Pacing: A Randomized Comparative Study Evaluating Mid‐Term Electromechanical and Clinical Effects

Although left ventricular (LV) pacing has been proposed as an alternative to biventricular (BIV) pacing for heart failure (HF) patients, few comparative data are available on the electromechanical effects of these pacing modalities at mid-term follow-up. To investigate the clinical and echocardiographic effects of LV versus BIV pacing in a mid-term randomized study. After implantation of a device with LV/BIV pacing capabilities, 22 patients with chronic HF and left bundle branch block were randomized to LV or BIV pacing. Patients were assessed both preimplantation and after 3 months by clinical examination, ECG and echocardiography with pulsed tissue Doppler imaging. At 3 months LV pacing improved clinical parameters, LV ejection fraction (+5%, range 5-8%, P = 0.007) and intraventricular dyssynchrony (-40 ms, range -50 to -15 ms, in septal to lateral delay, P = 0.008) to a similar extent to BIV pacing. A decrease in interventricular mechanical delay (-25 ms, range -40 to -5 ms, P = 0.008) and QRS duration (-28 ms, range -40 to -5 ms, P = 0.008) was observed in BIV, but not in LV patients. In this pilot evaluation, LV pacing appeared to be associated with clinical benefits similar to BIV pacing at mid-term follow-up, and this was combined with an improvement in intraventricular dyssynchrony, regardless of variations in interventricular dyssynchrony and QRS duration. Echocardiographic evaluation of intraventricular dyssynchrony seems to be an appropriate method for assessing the chronic response to LV pacing.

The Impact of Cardiac Resynchronization Therapy on Obstructive Sleep Apnea in Heart Failure Patients: A Pilot Study

Cardiac resynchronization therapy (CRT) has been shown to improve cardiac function and reduce Cheyne-Stokes respiration but has not been evaluated in patients with obstructive sleep apnea (OSA). In this pilot study, we investigated the impact of both CRT and CRT plus increased rate pacing in heart failure (ie, congestive heart failure [CHF]) patients with OSA. We hypothesized that through increased cardiac output CRT/pacing would reduce obstructive events and daytime symptoms of sleepiness. Full polysomnograms were performed on CHF patients who were scheduled for CRT, and those patients with an apnea-hypopnea index (AHI) of > 5 events per hour were approached about study enrollment. Patients had a pre-CRT implant baseline echocardiogram and an echocardiogram a mean (+/- SEM) duration of 6.6 +/- 1.4 months post-CRT implant; polysomnography; and responded to the Minnesota Living with Heart Failure questionnaire, the Epworth sleepiness scale, and the Functional Outcomes of Sleep Questionnaire. An additional third polysomnography was performed combining CRT with a pacing rate of 15 beats/min above the baseline sleeping heart rate within 1 week of the second polysomnography. Assessments for the change in cardiac output during the polysomnography were performed using circulation time to pulse oximeter as a surrogate. Twenty-four patients were screened, and 13 patients (mean age, 68.6 years; body mass index, 28.7 kg/m(2)) had evidence of OSA. The mean AHI decreased from 40.9 +/- 6.4 to 29.5 +/- 5.9 events per hour with CRT (p = 0.04). The mean baseline ejection fraction was 22 +/- 1.7% and increased post-CRT to 33.6 +/- 2.0% (p < 0.05). The reduction in AHI with CRT closely correlated with a decrease in circulation time (r = 0.89; p < 0.001) with CRT. Increased rate pacing made no additional impact on the AHI or circulation time. CRT had a limited impact on sleep architecture or daytime symptom scores. CRT improved cardiac function and reduced the AHI. Reduced circulatory delay likely stabilized ventilatory control systems and may represent a new therapeutic target in OSA.