How many patients with dilated cardiomyopathy may potentially benefit from cardiac resynchronization therapy?

Association between left bundle branch block and ventricular septal mid-wall fibrosis in patients with preserved left ventricular ejection fraction

BACKGROUND

The left bundle branch block (LBBB) is associated with ventricular septal mid-wall fibrosis (SMF) in patients with dilated cardiomyopathy (DCM). However, whether LBBB is also associated with SMF in patients with preserved left ventricular ejection fraction (LVEF) remains unclear.

METHODS

We performed a retrospective study of 210 patients with preserved LVEF (male, n = 116; female, n = 94; mean age, 44 ± 17 years). LBBB was defined as QRS duration ≥140 ms for men or ≥ 130 ms for women, QS or rS in V1-V2, mid-QRS notching or slurring in at least two leads (V1, V2, V5, V6, I, and aVL). SMF determined by late gadolinium-enhancement cardiovascular magnetic resonance was defined as stripe-like or patchy mid-myocardial hyper-enhancement in the interventricular septal segments.

RESULTS

SMF was detected in 24.8% (52/210) of these patients. The proportion of patients with SMF with LBBB was higher than the proportion of patients with SMF without LBBB (58.3% vs. 20.4%; P < 0.001). In the forward multivariate logistic analysis, LBBB (OR, 4.399; 95% CI, 1.774-10.904; P = 0.001) and age (OR, 1.028; 95% CI, 1.006-1.051; P = 0.011) were independently associated with SMF. The presence of LBBB showed a sensitivity of 27%%, specificity of 94%, positive predictive value of 58%%, and negative predictive value of 80% for the detection of SMF.

CONCLUSION

LBBB was significantly associated with SMF in hospitalized patients with preserved LVEF. Screening with a resting 12‑lead ECG may help to identify patients who are at a high risk of the presence of SMF.

Detection and management of arrhythmias in peripartum cardiomyopathy

Peripartum cardiomyopathy (PPCM) is an idiopathic dilated cardiomyopathy, in which previously healthy women present with heart failure secondary to left ventricular (LV) systolic dysfunction during the last months of pregnancy or up to 5 months postpartum. PPCM occurs worldwide. The incidence seems to be increasing, possibly due to increasing awareness of the condition and diagnosis thereof. Women diagnosed with PPCM present with symptoms and signs of heart failure, thromboembolism or arrhythmia. Although the incidence of arrhythmias in this condition is not well documented, patients with PPCM often have rhythm disturbances. Indeed, life-threating arrhythmias contribute significantly to sudden cardiac death (SCD) in this population, especially when patients have poor systolic function. In this review, we summarize the evidence on atrial and ventricular arrhythmias in PPCM, as detected by various diagnostic modalities. Furthermore, we summarize the management of arrhythmias in PPCM, as recommended by contemporary guidelines.

Review of eligibility for cardiac resynchronization therapy

Cardiac resynchronization therapy (CRT) is underused. Recent guidelines have expanded indications for CRT to include less severe symptoms but now favor left bundle branch block morphology in patients with moderate QRS prolongation. The prevalence of CRT eligibility according to historical and current guidelines is uncertain. The aim of this review was to identify and synthesize all existing published research reporting the prevalence of CRT eligibility. A systematic review of electronic databases including MEDLINE, Embase, and the Cochrane Library was performed. The primary outcome was the proportion of patients eligible for CRT according to historical and current criteria. Secondary outcomes included the individual components of eligibility (the ejection fraction, symptoms, and QRS duration and morphology). Eligibility estimates were pooled using random-effects models because of marked heterogeneity in between-study variance. Thirty studies were identified. No study used current guideline criteria. On the basis of historical criteria, 11 ± 3% of ambulatory and 9 ± 3% of hospitalized patients are eligible for CRT. However, New York Heart Association class II in current guidelines is at least as frequent as New York Heart Association III or IV. Approximately 1/3 of patients have QRS prolongation, 2/3 of whom have left bundle branch block. Only a few patients have non-left bundle branch block with QRS duration <150 ms. Medical contraindication or ineligibility was rarely assessed. In conclusion, current estimates of need are outdated. Inclusion of milder symptoms potentially doubles the eligible population. Studies in unselected cohorts are needed to accurately define the individual components of eligibility, together with the prevalence and reasons for ineligibility.

Rates and reasons for device-based guideline eligibility in patients with heart failure

BACKGROUND

Implantable cardioverter-defibrillators (ICDs) and cardiac resynchronization therapy (CRT) are recommended by guidelines for patients with heart failure (HF) meeting specific criteria. Uncertainty exists regarding estimates of device eligibility, related in part to the method of assessing for guideline nonadherence.

OBJECTIVE

The aim of this study was to identify the rates of guideline eligibility and device utilization after accounting for reasons for not receiving an ICD or CRT.

METHODS

Patients were identified from 2006 to 2011 in a tertiary Heart Function Clinic in Canada. The chart-level data were collected that would indicate guideline eligibility and nonadherence.

RESULTS

A total of 762 patients with HF were included (mean age 66 years; 527 (69%) were males; median left ventricular ejection fraction 33%). Over follow-up, 331 patients (43%) were never guideline eligible whereas 431 (57%) were guideline eligible for a device. Yearly rates for ICD and CRT adherence in "guideline-eligible" patients ranged from 59% to 68% and from 66% to 81%, respectively. "Patient preference" was the most commonly documented reason for guideline nonadherence in eligible patients. After removal of patients with reasons for nonadherence, rates of ICD and CRT adherence in the "truly eligible" patients were found to be higher (70%-81% and 71%-88%, respectively) than those in guideline-eligible patients. Independent predictors of device nonadherence in truly eligible patients were age >75 years, QRS duration <120 ms, left ventricular ejection fraction <30%, and female sex.

CONCLUSION

Based on chart-level data, utilization rates of device-based therapies in patients with HF appear much higher than those of prior registry-based estimates. Given the importance of patient preferences for lack of device use, future quality-of-care metrics based on guideline adherence should capture detailed chart-level data and patient preferences.

Cardiac resynchronization therapy: a breakthrough in heart failure management

Heart failure is now considered an epidemic. In patients with heart failure, electrical and mechanical dyssynchrony, evident primarily as prolongation of the QRS-complex on the surface electrocardiogram, is associated with detrimental effects on the cardiovascular system at several levels. In the past 10 years, studies have demonstrated that by stimulating both cardiac ventricles simultaneously, or almost simultaneously [cardiac resynchronization therapy (CRT)], the adverse effects of dyssynchrony can be overcome. Here, we provide a comprehensive overview of different aspects of CRT including the rationale behind and evidence for efficacy of the therapy. Issues with regard to gender effects and patient follow-up as well as a number of unresolved concerns will also be discussed.

QRS duration is associated with atrial fibrillation in patients with left ventricular dysfunction

BACKGROUND

QRSduration (QRSd) is associated with higher mortality and morbidity in patients with left ventricular (LV) dysfunction. The association between QRSd and atrial fibrillation (AF) has not been studied in this patient population.

OBJECTIVES

To investigate the association between QRSd and AF in patients with LV dysfunction.

METHODS

Data were obtained from the National Registry to Advance Heart Health (ADVANCENT) registry, a prospective multicenter registry of patients with left ventricular ejection fraction (LVEF) < or = 40%. A total of 25 268 patients from 106 centers in the United States, were enrolled between June 2003 and November 2004. Demographic and clinical characteristics of patients were collected from interviews and medical records.

RESULTS

: Mean age was 66.3+/-13 years, 71.5% were males, and 81.9% were white. A total of 14 452 (57.8%) patients had a QRSd < 120 ms, 5304 (21.2%) had a QRSd between 120 and 150 ms, and 5269 (21%) had a QRSd > 150 ms. Atrial fibrillation occurred in 20.9%, 27.5%, and 35.5% of patients in the QRS groups, respectively (P < 0.0001). After adjusting for potential AF risk factors (age, gender, race, body mass index, hypertension, diabetes, renal failure, cancer, lung disease, New York Heart Association [NYHA] class, ejection fraction, etiology of cardiomyopathy) and the use of angiotensin-converting enzyme inhibitors, angiotensin receptor blockers, beta-blockers, and lipid lowering drugs, QRS duration remained independently associated with AF (odds ratio: 1.20, 95% confidence interval: 1.14-1.25).

CONCLUSION

In this large cohort of patients, QRSd was strongly associated with AF and therefore may predict the occurrence of this arrhythmia in patients with LV dysfunction. This association persisted after adjusting for disease severity, comorbid conditions, and the use of medications known to be protective against AF.

Effect of medical therapy on left ventricular ejection fraction in patients with systolic heart failure and narrow QRS duration with and without ischemic heart disease and left ventricular mechanical dyssynchrony

We studied 99 consecutive patients with class III-IV systolic heart failure with a left ventricular ejection fraction (LVEF) < or =35% and a QRS duration <120 milliseconds. Patients with cardiac resynchronization therapy were excluded. Echocardiography was performed in all patients before and after optimal standard heart failure therapy. The septal-to-posterior wall motion delay (SPWMD) > or =130 milliseconds on echocardiogram was defined as left ventricular mechanical dyssynchrony (LVMD). Sixty-nine of 99 patients (70%) had ischemic heart disease. During follow-up of 15.2 +/- 9.8 months, LVEF improvement > or =15% was greater patients in nonischemic group (50%, 15/30) than in ischemic group (9%, 6/69; P < 0.001). After adjustment for age, gender, and clinical and echocardiographic characteristics, ischemic heart disease and grade of coronary disease were persistently related to LVEF improvement > or =15% (P = 0.03 and 0.02, respectively). Twenty of 99 patients (20%) had SPWMD > or =130 milliseconds (LVMD group), and 79 of 99 patients (80%) had SPWMD <130 milliseconds (non-LVMD group). LVEF increased in both groups (P = 0.005) during follow-up, but the percentage of patients with LVEF improvement > or =15% in LVMD was greater compared with patients without LVMD (40% versus 16%, respectively, P = 0.03). In conclusion, the improvement of LVEF in patients with systolic heart failure and narrow QRS was greater in patients with nonischemic heart disease and LVMD compared with patients with ischemic heart disease and absence of LVMD during medical therapy without cardiac resynchronization therapy.

Standard values for real-time transthoracic three-dimensional echocardiographic dyssynchrony indexes in a normal population

BACKGROUND

There is a paucity of information describing the real-time 3-dimensional echocardiography (RT3DE) and dyssynchrony indexes (DIs) of a normal population. We evaluate the RT3DE DIs in a population with normal electrocardiograms and 2- and 3-dimensional echocardiographic analyses. This information is relevant for cardiac resynchronization therapy.

METHODS

We evaluated 131 healthy volunteers (73 were male, aged 46 +/- 14 years) who were referred for routine echocardiography; who presented normal cardiac structure on electrocardiography, 2-dimensional echocardiography, and RT3DE; and who had no history of cardiac diseases. We analyzed 3-dimensional left ventricular ejection fraction, left ventricle end-diastolic volume, left ventricle end-systolic volume, and left ventricular systolic DI% (6-, 12-, and 16-segment models). RT3DE data were analyzed by quantifying the statistical distribution (mean, median, standard deviation [SD], relative SD, coefficient of skewness, coefficient of kurtosis, Kolmogorov-Smirnov test, D'Agostino-Pearson test, percentiles, and 95% confidence interval).

RESULTS

Left ventricular ejection fraction ranged from 50% to 80% (66.1% +/- 7.1%); left ventricle end-diastolic volume ranged from 39.8 to 145 mL (79.1 +/- 24.9 mL); left ventricle end-systolic volume ranged from 12.9 to 66 mL (27 +/- 12.1 mL); 6-segment DI% ranged from 0.20% to 3.80% (1.21% +/- 0.66%), median: 1.06, relative SD: 0.5482, coefficient of skewness: 1.2620 (P < .0001), coefficient of Kurtosis: 1.9956 (P = .0039); percentile 2.5%: 0.2900, percentile 97.5%: 2.8300; 12-segment DI% ranged from 0.22% to 4.01% (1.29% +/- 0.71%), median: 1.14, relative SD: 0.95, coefficient of skewness: 1.1089 (P < .0001), coefficient of Kurtosis: 1.6372 (P = .0100), percentile 2.5%: 0.2850, percentile 97.5%: 3.0700; and 16-segment DI% ranged from 0.29% to 4.88% (1.59 +/- 0.99), median: 1.39, relative SD: 0.56, coefficient of skewness: 1.0792 (P < .0001), coefficient of Kurtosis: 0.9248 (P = .07), percentile 2.5%: 0.3750, percentile 97.5%: 3.750.

CONCLUSION

This study allows for the quantification of RT3DE DIs in normal subjects, providing a comparison for patients with heart failure who may be candidates for cardiac resynchronization therapy.

The cost of medical management in advanced heart failure during the final two years of life

OBJECTIVE

To examine patterns of resource use and the cost of care for patients with advanced heart failure treated with medical management (MM) during the final 2 years of life.

METHODS AND RESULTS

The study population (n=47, mean age 70.4 years+/-7.06) included patients randomized to the MM arm of the Randomized Evaluation of Mechanical Assistance for the Treatment of Congestive Heart Failure trial. Inpatient and outpatient use data were obtained from the clinical dataset and Centers for Medicare and Medicaid Services (beginning January 1, 1998). Cost and resource use were tracked from the date of death (t(d)) backward in 3-month intervals (eg, t(d-1), t(d-2)). In the primary analysis, costs were summed across intervals. The mean cost of MM in the final 2 years of life was $156,169, with 50.5% ($78,880.39) expended in the final 6 months. The mean quarterly cost increased (P < .01) 4.9-fold from t(d-8) ($8,816 +/- $14,270) to t(d-1) ($42,836 +/- $41,407). The number of inpatient days increased (P < .01) 6.6-fold from 3.8+/-4.7 days to 22.2+/-23.5 days during the same time intervals.

CONCLUSION

This current economic analysis extends on previous findings by demonstrating that medical therapy in advanced and end-stage heart failure is associated with significant costs and resource consumption; these costs and resource consumption increase significantly as death approaches.

Prevalence and prognostic impact of bundle branch block in patients with heart failure: evidence from the CHARM programme

BACKGROUND

Bundle branch block (BBB) is a powerful independent predictor of cardiovascular mortality in patients with heart failure (HF) and reduced left ventricular ejection fraction (LVEF). The prognostic implications in HF with preserved systolic function (HF-PSF) are less well understood.

METHODS

The Candesartan in Heart failure: Assessment of Reduction in Mortality and morbidity (CHARM) programme randomised 7599 patients with symptomatic HF to receive candesartan or placebo. The primary outcome comprised cardiovascular death or HF hospitalisation. The relative risk conveyed by BBB relative to a normal electrocardiogram was examined.

RESULTS

The prevalence of BBB was significantly lower in patients with preserved compared with reduced systolic function (CHARM-Preserved 14.4%, Alternative 29.6%, Added 30.5%), p<0.0001. Overall, the adjusted hazard ratio for the primary outcome was 1.48 (95% confidence interval 1.22-1.78), p<0.0001, reflecting increased risk in patients with reduced LVEF (1.72 [1.28-2.31], p=0.0003). The apparently more modest risk among patients with HF-PSF was significant in unadjusted (1.80 [1.37-2.37], p<0.0001) but not adjusted analysis (1.16 [0.88-1.54], p=0.2897). However, no formal statistical difference was observed between the two cohorts, and interpretation is limited by the unknown prevalence of left and right BBB morphologies in each. Comparing BBB presence with absence yielded qualitatively similar results.

CONCLUSION

The simple clinical finding of BBB is a powerful independent predictor of worse clinical outcomes in patients with HF and reduced LVEF. It is less frequent, with a more modest predictive effect, in patients with preserved systolic function.

Significance of QRS complex duration in patients with heart failure

Prolongation of QRS (> or =120 ms) occurs in 14% to 47% of heart failure (HF) patients. Left bundle branch block is far more common than right bundle branch block. Left-sided intraventricular conduction delay is associated with more advanced myocardial disease, worse left ventricular (LV) function, poorer prognosis, and a higher all-cause mortality rate compared with narrow QRS complex. It also predisposes heart failure patients to an increased risk of ventricular tachyarrhythmias, but the incidence of cardiac or sudden death remains unclear because of limited observations. A progressive increase in QRS duration worsens the prognosis. No electrocardiographic measure is specific enough to provide subgroup risk categorization for excluding or selecting HF patients for prophylactic implantable cardioverter-defibrillator (ICD) therapy. In ICD patients with HF, a wide underlying QRS complex more than doubles the cardiac mortality compared with a narrow QRS complex. There is a high incidence of an elevated defibrillation threshold at the time of ICD implantation in patients with QRS > or =200 ms. Mechanical LV dyssynchrony potentially treatable by ventricular resynchronization occurs in about 70% of HF patients with left-sided intraventricular conduction delay, a fact that would explain the lack of therapeutic response in about 30% of patients subjected to ventricular resynchronization according to standard criteria relying on QRS duration. The duration of the basal QRS complex does not reliably predict the clinical response to ventricular resynchronization, and QRS narrowing after cardiac resynchronization therapy does not correlate with hemodynamic and clinical improvement. Mechanical LV dyssynchrony is best shown by evolving echocardiographic techniques (predominantly tissue Doppler imaging) currently in the process of standardization.

Different criteria of cardiac resynchronization therapy and their prognostic value for worsening heart failure or major arrhythmic events in patients with idiopathic dilated cardiomyopathy

There are still controversies about pertinent criteria for cardiac resynchronization therapy (CRT) and prophylactic indications for biventricular cardioverter-defibrillators, particularly in idiopathic dilated cardiomyopathy (IDC). This study compared several criteria for resynchronization therapy in IDC among those of several completed trials. In 201 patients with IDC, the relative risk for (1) death from heart failure (HF) or heart transplantation and (2) sudden death or sustained ventricular tachyarrhythmia were calculated separately according to the inclusion criteria of the Multisite Stimulation in Cardiomyopathy (MUSTIC), InSync, Multicenter InSync Randomized Clinical Evaluation (MIRACLE), Pacing Therapies for Congestive Heart Failure (PATH-CHF), Comparison of Medical Therapy, Pacing, and Defibrillation in Heart Failure (COMPANION), and CONTAK studies. The percentage of patients meeting the criteria ranged from 6% for those of MUSTIC to 23% for those of CONTAK. In a follow-up of 51 +/- 42 months, 28 patients died (15 from progressive HF, 13 from sudden death), 20 underwent heart transplantation, and 12 had sustained ventricular tachyarrhythmia. Relative risks of worsening HF ranged from 3.14 (95% confidence interval [CI] 1.41 to 6.99, p = 0.005) for the MIRACLE criteria to 4.63 (95% CI 1.76 to 12.2, p = 0.0019) for the MUSTIC criteria. Only the CONTAK criteria were significantly associated with a risk for major arrhythmic events (2.65, 95% CI 1.19 to 5.95, p = 0.018). Arrhythmic events constituted 16% of all cardiac events for the MUSTIC patients, 11% for InSync patients, 31% for PATH-CHF patients, 36% for MIRACLE patients, 38% for COMPANION patients, and 42% for CONTAK patients. In conclusion, in IDC, the less restrictive criteria for CRT were associated with the greatest risk for arrhythmic events. In contrast, patients with the MUSTIC criteria for CRT mainly had a risk for worsening HF and may not benefit from biventricular cardioverter-defibrillators.

Evidence of Structural Remodeling in the Dyssynchronous Failing Heart

Ventricular remodeling of both geometry and fiber structure is a prominent feature of several cardiac pathologies. Advances in MRI and analytical methods now make it possible to measure changes of cardiac geometry, fiber, and sheet orientation at high spatial resolution. In this report, we use diffusion tensor imaging to measure the geometry, fiber, and sheet architecture of eight normal and five dyssynchronous failing canine hearts, which were explanted and fixed in an unloaded state. We apply novel computational methods to identify statistically significant changes of cardiac anatomic structure in the failing and control heart populations. The results demonstrate significant regional differences in geometric remodeling in the dyssynchronous failing heart versus control. Ventricular chamber dilatation and reduction in wall thickness in septal and some posterior and anterior regions are observed. Primary fiber orientation showed no significant change. However, this result coupled with the local wall thinning in the septum implies an altered transmural fiber gradient. Further, we observe that orientation of laminar sheets become more vertical in the early-activated septum, with no significant change of sheet orientation in the late-activated lateral wall. Measured changes in both fiber gradient and sheet structure will affect both the heterogeneity of passive myocardial properties as well as electrical activation of the ventricles.

Real-Time Three-Dimensional Echocardiography

Background— Left ventricular (LV) mechanical dyssynchrony (LVMD) has emerged as a therapeutic target using cardiac resynchronization therapy (CRT) in selected patients with chronic heart failure. Current methods used to evaluate LVMD are technically difficult and do not assess LVMD of the whole LV simultaneously. We developed and validated real-time 3D echocardiography (RT3DE) as a novel method to assess global LVMD.

Methods and Results— Eighty-nine healthy volunteers and 174 unselected patients referred for routine echocardiography underwent 2D echocardiography and RT3DE. RT3DE data sets provided time-volume analysis for global and segmental LV volumes. A systolic dyssynchrony index (SDI) was derived from the dispersion of time to minimum regional volume for all 16 LV segments. Healthy subjects and patients with normal LV systolic function had highly synchronized segmental function (SDI, 3.5±1.8% and 4.5±2.4%; P =0.7). SDI increased with worsening LV systolic function regardless of QRS duration (mild, 5.4±0.83%; moderate, 10.0±2%; severe LV dysfunction, 15.6±1%; P for trend <0.001). We found that 37% of patients with moderate to severe LV systolic dysfunction had significant dyssynchrony with normal QRS durations (SDI, 14.7±1.2%). Twenty-six patients underwent CRT. At long-term follow-up, responders demonstrated reverse remodeling after CRT with a significant reduction in SDI (16.9±1.1% to 6.9±1%; P <0.0001) and end-diastolic volume (196.6±17.3 to 132.1±13.5 mL; P <0.0001) associated with an increase in LV ejection fraction (17±2.2% to 31.6±2.9%; P <0.0001).

Conclusions— RT3DE can quantify global LVMD in patients with and without QRS prolongation. RT3DE represents a novel technique to identify chronic heart failure patients who may otherwise not be considered for CRT.

How many patients with heart failure are eligible for cardiac resynchronization? Insights from two prospective cohorts

AIMS

To determine what proportion of patients with heart failure are eligible for cardiac resynchronization therapy (CRT).

METHODS AND RESULTS

Eligibility criteria from the trials establishing the efficacy of CRT were applied to two prospective cohorts: the first enrolled patients with newly diagnosed heart failure discharged from 103 hospitals between April 1999 and March 2001 ('the hospital discharge cohort'); the second enrolled patients seen in a specialized clinic between August 2003 and January 2004 ('the specialty clinic cohort'). In the hospital discharge cohort, 73 patients (3% of the 2640 patients with ischaemic or dilated cardiomyopathy and 1% of all 9096 patients with heart failure discharged alive) met trial eligibility criteria: LVEF< or =0.35, QRS > or =120 ms, sinus rhythm, and NYHA class III or IV symptoms despite the treatment with ACE-inhibitor/angiotensin receptor blocker and beta-blocker. In the specialty clinic cohort, 54 patients (21% of the 263 patients with ischaemic or dilated cardiomyopathy and 17% of all 309 patients with heart failure) met these criteria. If persistent symptoms despite taking spironolactone were required for CRT eligibility, then the proportions qualifying dropped to 1% in the hospital discharge cohort and 18% in the specialty clinic cohort.

CONCLUSION

Few heart failure patients meet trial eligibility criteria for CRT.

Potential Candidates for Cardiac Resynchronization Therapy in Japanese Patients With Idiopathic Dilated Cardiomyopathy-A Niigata Multicenter Study of DCM-

BACKGROUND

The purpose of this study was to assess the candidates suitable for cardiac resynchronization therapy (CRT) and to examine the significance of the QRS duration in Japanese patients with idiopathic dilated cardiomyopathy (DCM).

METHODS AND RESULTS

The study population consisted of 357 patients. The selection criteria for candidates suitable for CRT were QRS duration =130 ms, left ventricular ejection fraction (LVEF) =35% and New York Heart Association (NYHA) functional class III or IV by ACC/AHA/NASPE 2002 guidelines. We divided the study population into 2 groups: group A with a QRS duration <130 ms, and group B with a QRS duration =130 ms. In 25 of the 375 patients (7.0%), all the criteria were fulfilled. Group B had a significantly larger left ventricular diameter end-diastole and end-systole than group A (P<0.0001). Group B had a lower LVEF (P<0.0001). There was a fair inverse correlation (r=-0.58, P<0.0001) between the length of the QRS duration and LVEF.

CONCLUSION

Approximately 7% of the Japanese patients with DCM are CRT candidates. In the present study, we found that prolonged QRS duration was associated with poor systolic function.