Ventricular arrhythmia risk is associated with myocardial scar but not with response to cardiac resynchronization therapy

Tissue characterization using cardiac magnetic resonance imaging and response to cardiac resynchronization therapy

AIMS

Cardiac magnetic resonance (CMR) imaging for tissue characterization offers valuable insights for risk stratification among patients with cardiomyopathy. This study aimed to assess the prognostic value of CMR-based tissue characterization in predicting response to cardiac resynchronization therapy (CRT) in patients with non-ischaemic cardiomyopathy (NICM).

METHODS AND RESULTS

Retrospective analysis was performed on CMR data from NICM patients before CRT implantation. Various CMR parameters, including the late gadolinium enhancement (LGE), native T1, T2, and extracellular volume (ECV), were analysed. Among the 101 patients (mean age: 66 years, male: 52.5%), 72 (71.3%) were CRT responders. The CRT responders had lower LGE burden (13.1 vs. 35.3%, P < 0.001), native T1 (1334.5 vs. 1371.6 ms, P = 0.012), T2 (42.2 vs. 45.7 ms, P < 0.001), and ECV (30.8 vs. 36.8%, P < 0.001) compared with CRT non-responders. After adjusting for other risk factors, LGE burden ≤ 20% [odds ratio (OR): 22.61, 95% confidence interval (CI): 4.73-176.68, P < 0.001], ECV ≤ 34% (OR: 15.93, 95% CI: 3.01-115.13, P = 0.002), and T2 ≤ 45 ms (OR: 8.10, 95% CI: 1.82-43.75, P = 0.008) were identified as predictors of good CRT response and favourable clinical outcomes (log-rank P < 0.001).

CONCLUSION

Cardiac magnetic resonance-based tissue parameters effectively predict CRT response and clinical outcomes in patients with NICM, independently of conventional predictors.

Ascertaining the prognostic role of cardiac resynchronisation therapy in cardiac sarcoidosis: A comparison with ischaemic cardiomyopathy

BACKGROUND

Cardiac Resynchronisation Therapy (CRT) has demonstrated short and long-term benefit in heart failure with reduced ejection fraction (HFrEF), including ischaemic (ICM) and non-ischaemic cardiomyopathy. However, there is a paucity of evidence regarding its role in cardiac sarcoidosis (CS).

METHODS

Consecutive CS patients with CRT and baseline left ventricle ejection fraction (LVEF)≤40 referred to one specialist hospital in London between November 2008-March 2023 were retrospectively reviewed. The baseline characteristics, short-term echocardiographic, clinical parameters and long-term primary and secondary outcomes were compared against a cohort of ICM patients with CRT and baseline LVEF≤40. Patients with incomplete follow-up were excluded. The primary endpoint was a composite of all-cause mortality, cardiac transplantation or heart failure hospitalisation. Secondary endpoint included ventricular arrhythmic events.

RESULTS

63 CS and 93 ICM patients were analysed. A greater proportion of ICM patients male with older ages overall (both p < 0.01), whereas a larger proportion of CS patients had atrioventricular block and heart failure hospitalisations (both p < 0.01). Both cohorts demonstrated significant serial increase in left ventricular (LV) ejection fraction and reduction in LV end-systolic and end-diastolic volumes (p < 0.01). After a mean follow up of 40.9 (±32.0) months, the primary and secondary endpoint was reached by significantly more CS patients (log-rank p = 0.008 and log-rank p = 0.004). Age (HR: 1.12 (95 %CI 1.06-1.17, p < 0.001) and presence of CS (HR: 8.33 (95 %CI 3.03-22.93, p < 0.001) were independent predictors of the primary endpoint on multivariable analysis.

CONCLUSION

CS patients with CRT demonstrated reverse remodelling, but had adverse long-term primary and secondary outcomes when compared to ICM patients.

Late gadolinium enhancement and outcome of cardiac resynchronization therapy in non-ischemic cardiomyopathy

BACKGROUND

It is uncertain whether CRT with defibrillator (CRTD) is superior to CRT with pacemaker (CRTP) in NICM. Patients with low arrhythmic risk and high probability of response to CRT might be ideal candidates for CRTP. We aimed to evaluate predictors of ventricular arrhythmias and of echocardiographic response to cardiac resynchronization therapy (CRT) in non-ischemic cardiomyopathy (NICM).

METHODS

Multicenter, retrospective observational study of NICM patients with left ventricular ejection fraction (LVEF) ≤35 %, cardiac magnetic resonance with analysis of late gadolinium enhancement (LGE) available and de-novo CRT implant. Echocardiographic response to CRT was defined as an improvement in LVEF ≥10 %. The combined arrhythmic endpoint included sustained ventricular tachycardia, appropriate ICD therapy, resuscitated cardiac arrest and sudden death.

RESULTS

We included 167 patients, with a median follow-up of 63 months. LGE was present in 77 (46 %). Response to CRT occurred in 68 % of patients, more frequently in LGE- than in LGE+ (81 % vs 53 %, p < 0.001). Absence of LGE (OR 3.4, p = 0.002), was an independent predictor of response to CRT. The arrhythmic endpoint occurred in 19 patients (11 %). Among LGE- patients there were zero arrhythmic events as compared to a 25 % cumulative incidence in LGE+ (p < 0.001). Presence of LGE (HR 22.5, p < 0.001), was an independent predictor of the arrhythmic endpoint.

CONCLUSION

Absence of LGE identifies patients at minimal arrhythmic risk and with high probability of response to CRT. Thus, they might be ideal candidates to CRT-P.

A Comparison of the Association of Septal Scar Burden on Responses to LBBAP-CRT and BVP-CRT

BACKGROUND

Left bundle branch area pacing (LBBAP) is an alternative to biventricular pacing (BVP) for cardiac resynchronization therapy (CRT). However, despite the presence of left bundle branch block, whether cardiac substrate may influence the effect between the 2 strategies is unclear.

OBJECTIVES

This study aims to assess the association of septal scar on reverse remodeling and clinical outcomes of LBBAP compared with BVP.

METHODS

We analyzed patients with nonischemic cardiomyopathy who had CRT indications undergoing preprocedure cardiac magnetic resonance examination. Changes in left ventricular ejection fraction (LVEF) and echocardiographic response (ER) (≥5% absolute LVEF increase) were assessed at 6 months. The clinical outcome was the composite of all-cause mortality, heart failure hospitalization, or major ventricular arrhythmia.

RESULTS

There were 147 patients included (51 LBBAP and 96 BVP). Among patients with low septal scar burden (below median 5.7%, range: 0% to 5.3%), LVEF improvement was higher in the LBBAP than the BVP group (17.5% ± 10.9% vs 12.3% ± 11.8%; P = 0.037), with more than 3-fold increased odds of ER (OR: 4.35; P = 0.033). In high sepal scar subgroups (≥5.7%, range: 5.7%-65.9%), BVP trended towards higher LVEF improvement (9.2% ± 9.4% vs 6.4% ± 12.4%; P = 0.085). Interaction between septal scar burden and pacing strategy was significant for ER (P = 0.002) and LVEF improvement (P = 0.011) after propensity score adjustment. During median follow-up of 33.7 (Q1-Q3: 19.8-42.1) months, the composite clinical outcome occurred in 34.7% (n = 51) of patients. The high-burden subgroups had worse clinical outcomes independent of CRT method.

CONCLUSIONS

Remodeling response to LBBAP and BVP among nonischemic cardiomyopathy patients is modified by septal scar burden. High septal scar burden was associated with poor clinical prognosis independent of CRT methods.

Impact of Cardiac Magnetic Resonance to Arrhythmic Risk Stratification in Nonischemic Cardiomyopathy

Left ventricular ejection fraction-based arrhythmic risk stratification in nonischemic cardiomyopathy (NICM) is insufficient and has led to the failure of primary prevention implantable cardioverter defibrillator trials, mainly due to the inability of selecting patients at high risk for sudden cardiac death (SCD). Cardiac magnetic resonance offers unique opportunities for tissue characterization and has gained a central role in arrhythmic risk stratification in NICM. The presence of myocardial scar, denoted by late gadolinium enhancement, is a significant, independent, and strong predictor of ventricular arrhythmias and SCD with high negative predictive value. T1 maps and extracellular volume fraction, which are able to quantify diffuse fibrosis, hold promise as complementary tools but need confirmatory results from large studies.

Twenty-five years of research in cardiac imaging in electrophysiology procedures for atrial and ventricular arrhythmias

Catheter ablation is nowadays considered the treatment of choice for numerous cardiac arrhythmias in different clinical scenarios. Fluoroscopy has traditionally been the primary imaging modality for catheter ablation, providing real-time visualization of catheter navigation. However, its limitations, such as inadequate soft tissue visualization and exposure to ionizing radiation, have prompted the integration of alternative imaging modalities. Over the years, advancements in imaging techniques have played a pivotal role in enhancing the safety, efficacy, and efficiency of catheter ablation procedures. This manuscript aims to explore the utility of imaging, including electroanatomical mapping, cardiac computed tomography, echocardiography, cardiac magnetic resonance, and nuclear cardiology exams, in helping electrophysiology procedures. These techniques enable accurate anatomical guidance, identification of critical structures and substrates, and real-time monitoring of complications, ultimately enhancing procedural safety and success rates. Incorporating advanced imaging technologies into routine clinical practice has the potential to further improve clinical outcomes of catheter ablation procedures and pave the way for more personalized and precise ablation therapies in the future.

Age-stratified comparison of prognosis in cardiac resynchronization therapy with or without prophylactic defibrillator for nonischemic cardiomyopathy-a nationwide cohort study

AIMS

Prior studies have suggested that the benefit from primary preventive defibrillator treatment for patients with nonischemic cardiomyopathyy, treated with cardiac resynchronization therapy, may be age-dependent. We aimed to compare age-stratified mortality rates and mode of death in patients with nonischemic cardiomyopathy who are treated with either primary preventive cardiac resynchronization therapy with defibrillator (CRT-D) or CRT with pacemaker (CRT-P).

METHODS AND RESULTS

All patients with nonischemic cardiomyopathy and CRT-P or primary preventive CRT-D who were implanted in Sweden during the period 2005-2020 were included. Propensity scoring was used to create a matched cohort. Primary outcome was all-cause mortality within 5 years. In all, 4027 patients were included: 2334 with CRT-P and 1693 with CRT-D. Crude 5-year mortality was 635 (27%) vs. 246 (15%), P < 0.001. In Cox regression analysis, adjusted for clinically relevant covariables, CRT-D was independently associated with higher 5-year survival [0.72 (0.61-0.85), P < 0.001]. Cardiovascular mortality was similar between groups (62 vs. 64%, P = 0.64), but death from heart failure was more common in the CRT-D group (46 vs. 36%, P = 0.007). In the matched cohort (n = 2414), 5-year mortality was 21% (24 vs. 16%, P < 0.001). In age-stratified analyses, CRT-P was associated with higher mortality in age groups <60 years and 70-79 years, but there was no difference in age groups 60-69 years or 80-89 years.

CONCLUSION

In this nationwide registry-based study, patients with CRT-D had better 5-year survival compared to patients with CRT-P. The interaction between age and mortality reduction was not consistent, but patients with CRT-D aged <60 years had the largest absolute mortality reduction.

Late-onset and classic phenotypes of Fabry disease in males with the GLA-Thr410Ala mutation

OBJECTIVE

To present phenotypic characteristics and biomarkers of a family with the rare mutation Thr410Ala of the α-galactosidase A gene (T410A/GLA) causing Fabry disease (FD).

METHODS AND RESULTS

In a woman in her 60s with hypertrophic cardiomyopathy, T410A/GLA was found in screening for variants in 59 cardiomyopathy-related genes. Her son in his 40s, two granddaughters and two great grandsons carried T410A/GLA. The son had a history of hypertension and paroxysmal AF but no microalbuminuria or classic symptoms or signs of FD. Baseline α-galactosidase A enzyme (α-Gal A) activity varied from 0% to 26.5%. Cardiac MRI showed mild Fabry cardiomyopathy (FC). During 11 years of enzyme replacement therapy (ERT), FC progressed and he suffered sudden cardiac death in his 50s. The great grandsons with T410A/GLA had no active α-Gal A, high lyso-Gb₃ levels and normal cardiac imaging. They suffered from neuropathic pain and gastrointestinal symptoms and were started with ERT at the age under 10. Granddaughters with T410A/GLA had α-Gal A activities of 8-18 and 10% of normal. The older granddaughter in her 30s was diagnosed with incipient FC. Plasma lyso-Gb₃ analogues were elevated, markedly in the elder male with FC and moderately in the elder granddaughter. In young males with classic phenotype, plasma lyso-Gb₃ analogues were only slightly elevated.

CONCLUSIONS

The T410A/GLA mutation caused late-onset FD with progressive cardiomyopathy in elder male, and classic FD in young males of the same family. Varying levels of α-Gal A and lyso-Gb₃ analogues reflected variable phenotype of FD in the family.

The role of cardiac magnetic resonance in identifying appropriate candidates for cardiac resynchronization therapy - a systematic review of the literature

Despite the strict indications for cardiac resynchronization therapy (CRT) implantation, a significant proportion of patients will fail to adequately respond to the treatment. This systematic review aims to present the existing evidence about the role of cardiac magnetic resonance (CMR) in identifying patients who are likely to respond better to the CRT. A systematic search in the MedLine database and Cochrane Library from their inception to August 2021 was performed, without any limitations, by two independent investigators. We considered eligible observational studies or randomized clinical trials (RCTs) that enrolled patients > 18 years old with heart failure (HF) of ischaemic or non-ischaemic aetiology and provided data about the association of baseline CMR variables with clinical or echocardiographic response to CRT for at least 3 months. This systematic review was performed in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA Statement). Following our search strategy, 47 studies were finally included in our review. CMR appears to have an additive role in identifying the subgroup of patients who will respond better to CRT. Specifically, the presence and the extent of myocardial scar were associated with increased non-response rates, while those with no scar respond better. Furthermore, existing data show that scar location can be associated with CRT response rates. CMR-derived markers of mechanical desynchrony can also be used as predictors of CRT response. CMR data can be used to optimize the position of the left ventricular lead during the CRT implantation procedure. Specifically, positioning the left ventricular lead in a branch of the coronary sinus that feeds an area with transmural scar was associated with poorer response to CRT. CMR can be used as a non-invasive optimization tool to identify patients who are more likely to achieve better clinical and echocardiographic response following CRT implantation.

Dispersion of repolarization increases with cardiac resynchronization therapy and is associated with left ventricular reverse remodeling

PURPOSE

Cardiac resynchronization therapy (CRT) reduces ventricular activation times and electrical dyssynchrony, however the effect on repolarization is unclear. In this study, we sought to investigate the effect of CRT and left ventricular (LV) remodeling on dispersion of repolarization using electrocardiographic imaging (ECGi).

METHODS

11 patients with heart failure and electrical dyssynchrony underwent ECGi 1-day and 6-months post CRT. Reconstructed epicardial electrograms were used to create maps of activation time, repolarization time (RT) and activation recovery intervals (ARI) and calculate measures of RT, ARI and their dispersion. ARI was corrected for heart rate (cARI).

RESULTS

Compared to baseline rhythm, LV cARI dispersion was significantly higher at 6 months (28.2 ± 7.7 vs 36.4 ± 7.2 ms; P = 0.03) but not after 1 day (28.2 ± 7.7 vs 34.4 ± 6.8 ms; P = 0.12). There were no significant differences from baseline to CRT for mean LV cARI or RT metrics. Significant LV remodeling (>15% reduction in end-systolic volume) was an independent predictor of increase in LV cARI dispersion (P = 0.04) and there was a moderate correlation between the degree of LV remodeling and the relative increase in LV cARI dispersion (R = -0.49) though this was not statistically significant (P = 0.12).

CONCLUSION

CRT increases LV cARI dispersion, but this change was not fully apparent until 6 months post implant. The effects of CRT on LV cARI dispersion appeared to be dependent on LV reverse remodeling, which is in keeping with evidence that the risk of ventricular arrhythmia after CRT is higher in non-responders compared to responders.

Timely and individualized heart failure management: need for implementation into the new guidelines

Due to remarkable improvements in heart failure (HF) management over the last 30 years, a significant reduction in mortality and hospitalization rates in HF patients with reduced ejection fraction (HFrEF) has been observed. Currently, the optimization of guideline-directed chronic HF therapy remains the mainstay to further improve outcomes for patients with HFrEF to reduce mortality and HF hospitalization. This includes established device therapies, such as implantable defibrillators and cardiac resynchronization therapies, which improved patients' symptoms and prognosis. Over the last 10 years, new HF drugs have merged targeting various pathways, such as those that simultaneously suppress the renin-angiotensin-aldosterone system and the breakdown of endogenous natriuretic peptides (e.g., sacubitril/valsartan), and those that inhibit the If channel and, thus, reduce heart rate (e.g., ivabradine). Furthermore, the treatment of patient comorbidities (e.g., iron deficiency) has shown to improve functional capacity and to reduce hospitalization rates, when added to standard therapy. More recently, other potential treatment mechanisms have been explored, such as the sodium/glucose co-transporter inhibitors, the guanylate cyclase stimulators and the cardiac myosin activators. In this review, we summarize the novel developments in HFrEF pharmacological and device therapy and discuss their implementation strategies into practice to further improve outcomes.

Segment Length in Cine Strain Analysis Predicts Cardiac Resynchronization Therapy Outcome Beyond Current Guidelines

BACKGROUND

Patients with a class I recommendation for cardiac resynchronization therapy (CRT) are likely to benefit, but the effect of CRT in class II patients is more heterogeneous and additional selection parameters are needed in this group. The recently validated segment length in cine strain analysis of the septum (SLICE-ESS_sep) measurement on cardiac magnetic resonance cine imaging predicts left ventricular functional recovery after CRT but its prognostic value is unknown. This study sought to evaluate the prognostic value of SLICE-ESS_sep for clinical outcome after CRT.

METHODS

Two hundred eighteen patients with a left bundle branch block or intraventricular conduction delay and a class I or class II indication for CRT who underwent preimplantation cardiovascular magnetic resonance examination were enrolled. SLICE-ESS_sep was manually measured on standard cardiovascular magnetic resonance cine imaging. The primary combined end point was all-cause mortality, left ventricular assist device, or heart transplantation. Secondary end points were (1) appropriate implantable cardioverter defibrillator therapy and (2) heart failure hospitalization.

RESULTS

Two-thirds (65%) of patients had a positive SLICE-ESS_sep ≥0.9% (ie, systolic septal stretching). During a median follow-up of 3.8 years, 66 (30%) patients reached the primary end point. Patients with positive SLICE-ESS_sep were at lower risk to reach the primary end point (hazard ratio 0.36; P<0.001) and heart failure hospitalization (hazard ratio 0.41; P=0.019), but not for implantable cardioverter defibrillator therapy (hazard ratio, 0.66; P=0.272). Clinical outcome of class II patients with a positive ESS_sep was similar to those of class I patients (hazard ratio, 1.38 [95% CI, 0.66-2.88]; P=0.396).

CONCLUSIONS

Strain assessment of the septum (SLICE-ESS_sep) provides a prognostic measure for clinical outcome after CRT. Detection of a positive SLICE-ESS_sep in patients with a class II indication predicts improved CRT outcome similar to those with a class I indication whereas SLICE-ESS_sep negative patients have poor prognosis after CRT implantation.

The prognostic role of late gadolinium enhancement on cardiac magnetic resonance in patients with nonischemic cardiomyopathy and reduced ejection fraction, implanted with cardioverter defibrillators for primary prevention. A systematic review and meta-analysis

BACKGROUND

Previous studies suggest that late gadolinium enhancement (LGE) on cardiac magnetic resonance (CMR) is associated with arrhythmic events in patients with nonischemic cardiomyopathy (NICM), while others have questioned the role of left ventricular ejection fraction (LVEF) as a sole predictor of future events.

OBJECTIVES

To evaluate the role of LGE on CMR in identifying patients with NICM and reduced LVEF for whom a benefit from defibrillator implantation for primary prevention is not anticipated, thus they are mainly exposed to potential risks.

METHODS

Major electronic databases were searched for studies reporting the incidence of appropriate device therapy (ADT), sudden cardiac death (SCD), and cardiac death based on the presence of LGE on CMR, among patients with NICM and reduced LVEF, implanted with a cardioverter defibrillator for primary prevention.

RESULTS

Eleven studies (1652 patients, 947 with LGE) were included in the final analysis. LGE presence was strongly associated with ADT (logOR: 1.95, 95%CI: 1.21-2.69) and cardiac death (logOR: 0.91, 95%CI: 0.14-1.68), but not with SCD (logOR: 0.26, 95%CI: -1.09-1.6). Diagnostic accuracy analysis demonstrated that contrast enhancement is a sensitive marker of future ADT and cardiac death (93%, 95%CI: 85.8-96.7%; 82.9%, 95%CI: 70.6-90.7%; respectively), with moderate specificity ( 44%, 95%CI: 27.2-62.6%; 37.7%, 95%CI: 23.4-54.6%; respectively).

CONCLUSION

LGE is a highly sensitive predictor of ADT and cardiac death in NICM patients implanted with a defibrillator for primary prevention. However, due to moderate specificity, derivation of a cutoff with adequate predictive values and probably a multifactorial approach are needed to improve discrimination of patients who will not benefit from ICDs.