Utilization and tolerance of beta-blockers among patients with AL amyloidosis

Mechanisms of damage and therapies for cardiac amyloidosis: a role for inflammation?

The term cardiac amyloidosis (CA) refers to the accumulation of extracellular amyloid deposits in the heart because of different conditions often affecting multiple organs including brain, kidney and liver. Notably, cardiac involvement significantly impacts prognosis of amyloidosis, with cardiac biomarkers playing a pivotal role in prognostic stratification. Therapeutic management poses a challenge due to limited response to conventional heart failure therapies, necessitating targeted approaches aimed at preventing, halting or reversing amyloid deposition. Mechanisms underlying organ damage in CA are multifactorial, involving proteotoxicity, oxidative stress, and mechanical interference. While the role of inflammation in CA remains incompletely understood, emerging evidence suggests its potential contribution to disease progression as well as its utility as a therapeutic target. This review reports on the cardiac involvement in systemic amyloidosis, its prognostic role and how to assess it. Current and emerging therapies will be critically discussed underscoring the need for further efforts aiming at elucidating CA pathophysiology. The emerging evidence suggesting the contribution of inflammation to disease progression and its prognostic role will also be reviewed possibly offering insights into novel therapeutic avenues for CA.

Effect of beta-blockade on mortality in patients with cardiac amyloidosis: A systematic review and meta-analysis

AIMS

The efficacy of beta-blockers in cardiac amyloidosis (CA) is unclear, and concerns persist that neurohormonal blockade could worsen symptoms of heart failure. We aimed to assess whether beta-blocker therapy is associated with improved survival in patients with CA.

METHODS AND RESULTS

We conducted a systematic review and meta-analysis to examine the impact of beta-blocker therapy on mortality in patients with CA. A search of MEDLINE and EMBASE was performed in August 2023. Data were extracted from observational studies and synthesized with pooling and random effects meta-analysis. Thirteen studies including 4215 patients with CA were incorporated in this review (3688 transthyretin amyloid cardiomyopathy (ATTR-CM), 502 light chain amyloid cardiomyopathy (AL-CM), 25 not specified; age 74.8 ± 5.5 years, 76% male). Over half of the cohort (52%) received beta-blockers and the rate of beta-blocker withdrawal was 28%. All-cause mortality was 33% (range: 13-51%) after a median follow-up ranging from 13 to 36 months. There was an inverse association between the pooled risk of mortality and the use of beta-blocker therapy at any time point (RR 0.48, 95% CI 0.29-0.80, I2 = 83%, P = 0.005, seven studies). There was no association between mortality and beta-blocker use (RR 0.65, 95% CI 0.29-1.47, I2 = 88%, P = 0.30) in the three studies that only included patients with ATTR-CM. The three studies that included patients with both ATTR-CM and AL demonstrated an association of beta-blocker use with reduced mortality (OR 0.43, 95% CI 0.29-0.63, I2 = 4%, P < 0.001). The only study that solely included 53 patients with AL-CM, demonstrated improved survival among the 53% who were able to tolerate beta-blocker therapy (RR 0.26, 95% CI 0.08-0.79, P = 0.02). The absence of information on staging of CA is an important limitation of this study.

CONCLUSIONS

Treatment with beta-blockers may be associated with a survival benefit in patients with CA, but these findings are subject to selection and survivor biases. Definitive prospective randomized trials of conventional heart failure therapies are needed in CA.

Arrhythmic Risk Stratification in Cardiac Amyloidosis: A Review of the Current Literature

Cardiac amyloidosis is the most frequent infiltrative disease caused by the deposition of misfolded proteins in the cardiac tissue, leading to heart failure, brady- and tachyarrhythmia and death. Conduction disorders, atrial fibrillation (AF) and ventricular arrhythmia (VA) significantly impact patient outcomes and demand recognition. However, several issues remain unresolved regarding early diagnosis and optimal management. Extreme bradycardia is the most common cause of arrhythmic death, while fast and sustained VAs can be found even in the early phases of the disease. Risk stratification and the prevention of sudden cardiac death are therefore to be considered in these patients, although the time for defibrillator implantation is still a subject of debate. Moreover, atrial impairment due to amyloid fibrils is associated with an increased risk of AF resistant to antiarrhythmic therapy, as well as recurrent thromboembolic events despite adequate anticoagulation. In the last few years, the aging of the population and progressive improvements in imaging methods have led to increases in the diagnosis of cardiac amyloidosis. Novel therapies have been developed to improve patients' functional status, quality of life and mortality, without data regarding their effect on arrhythmia prevention. In this review, we consider the latest evidence regarding the arrhythmic risk stratification of cardiac amyloidosis, as well as the available therapeutic strategies.

(Non)-Exertional Variables of Cardiopulmonary Exercise Testing in Heart Failure with and Without Cardiac Amyloidosis

PURPOSE OF REVIEW

Cardiac amyloidosis (CA) constitutes an important etiology of heart failure with preserved ejection fraction (HFpEF) or heart failure with mildly reduced ejection fraction (HFmrEF). Since patients with CA show early exhaustion, we aimed to investigate whether non-exertional variables of cardiopulmonary exercise testing (CPET) provide additional information in comparison to traditional peak oxygen consumption (VO2peak).

RECENT FINDINGS

We retrospectively investigated CPET variables of patients with HFpEF and HFmrEF with (n = 21) and without (n = 21, HF) CA at comparable age and ejection fraction. Exertional and non-exertional CPET variables as well as laboratory and echocardiographic markers were analyzed. The primary outcome was the difference in CPET variables between groups. The secondary outcome was rehospitalization in patients with CA during a follow-up of 24 months. Correlations between CPET, NTproBNP, and echocardiographic variables were calculated to detect patterns of discrimination between the groups. HF patients with CA were inferior to controls in most exertional and non-exertional CPET variables. Patients with CA were hospitalized more often (p = 0.002), and rehospitalization was associated with VE/VCO2 (p = 0.019), peak oxygen pulse (p = 0.042), the oxygen equivalent at the first ventilatory threshold (p = 0.003), circulatory (p = 0.024), and ventilatory power (p < .001), but not VO2peak (p = 0.127). Higher performance was correlated with lower E/e' and NTproBNP as well as higher resting heart rate and stroke volume in CA. Patients with CA displayed worse non-exertional CPET performance compared to non-CA HF patients, which was associated with rehospitalization. Differences between correlations of resting echocardiography and CPET variables between groups emphasize different properties of exercise physiology despite comparable ejection fraction.

Tolerability and effectiveness of beta-blockers in patients with cardiac amyloidosis: A systematic review and meta-analysis

OBJECTIVE

This systematic review aimed to assess the tolerability of patients with cardiac amyloidosis (CA) to beta-blockers (BBs) and evaluate its association with adverse outcomes.

METHODS

We performed a comprehensive search from January 1, 2000 to October 20, 2023. Studies examining BB use and tolerance or the relationship between BB use and outcomes in patients with CA were included. Pooled adjusted hazard ratios (aHRs) for all-cause mortality were calculated using random- and fixed-effects models.

RESULTS

Eight observational studies involving 4002 patients with CA (87.5% with transthyretin CA [ATTR-CA] and 12.5% with immunoglobulin light chain CA [AL-CA]) were assessed. BBs were used by 52.5% of the patients. However, 26.3% of the patients discontinued BBs because of hypotension, bradycardia, or fatigue. Regarding the association between BB use and all-cause death, four studies were identified that included 2874 patients with ATTR-CA and 16 patients with AL-CA. The meta-analysis revealed no apparent relationship between BB use and all-cause mortality (pooled aHR = 0.78, 95% confidence interval (CI) = 0.40-1.51). Two studies on patients with ATTR-CA found no impact of BB use on all-cause mortality in the subgroup with left ventricular ejection fraction (LVEF) > 40%, but conflicting results exist for those with LVEF ≤40% (pooled aHR = 0.78, 95% CI = 0.40-1.54).

CONCLUSION

The limited number of observational studies that predominantly enrolled patients with ATTR-CA showed that BBs were used in almost half of the patients with CA, with varying tolerability. However, no significant association was observed between BB use and all-cause mortality.

Beta-Adrenergic Antagonist Tolerance in Amyloid Cardiomyopathy

Background:

Beta-adrenergic antagonists or blockers (BB) are a cornerstone of cardiac therapy for multiple indications. However, BB are considered relatively contraindicated in amyloid cardiomyopathy due to poor tolerance. This intolerance is hypothesized to be due to concomitant neuropathy and significant restrictive cardiomyopathy. This study analyzes the incidence and characteristics of BB tolerance in patients with amyloid cardiomyopathy.

Methods

Through a single-center retrospective chart review, patients with amyloid cardiomyopathy, confirmed by endomyocardial biopsy or technetium-99 pyrophosphate scan, were identified and clinical data was collected. Statistical methods included Chi-square test and two sample t-tests.

Results

Of 135 cardiac amyloidosis patients, 27 patients (20.0%) had no BB use, 56 patients (41.5%) were current BB users, and 52 patients (38.5%) were prior BB users. The most frequent indications for BB use were heart failure, hypertension, coronary artery disease, and arrhythmia. The most common reason for stopping BB therapy was hypotension (62.8%) followed by fatigue, bradycardia, and orthostasis. Neurologic symptoms at the initial BB prescription or most recent evaluation were not significantly different between current and prior BB users. Their cardiovascular profiles were similar by ejection fraction, wall thickness, troponin I, and brain natriuretic peptide. There was no association for BB discontinuation based on amyloid subtype, sex, or race.

Conclusion

The majority of patients with amyloid cardiomyopathy were prescribed BB, and over half of these patients still tolerated BB therapy. Current and prior BB users had similar profiles from a cardiovascular and neurologic perspective, with no association identified to predict BB discontinuation.