Stroke volume and myocardial contraction fraction in transthyretin amyloidosis cardiomyopathy: A systematic review

Myocardial contraction fraction predicts outcomes in patients enrolled in the TOPCAT trial

BACKGROUND

Myocardial contraction fraction (MCF)-the ratio of left ventricular stroke volume to myocardial volume-is a volumetric measure of myocardial shortening that distinguishes between pathologic and physiologic hypertrophy. In this post-hoc analysis of the TOPCAT (Treatment of Preserved Cardiac Function Heart Failure with an Aldosterone Antagonist) trial, we investigated the prognostic value of MCF and its association with heterogeneity of treatment effect in heart failure with preserved ejection fraction (HFpEF).

METHODS

TOPCAT randomized patients with HFpEF to spironolactone or placebo. Patients with echocardiography data allowing for the calculation of MCF were included. The primary outcome was a composite of all-cause mortality, HF hospitalization, myocardial infarction, and stroke.

RESULTS

588 patients (median age 72.0 [63.0-79.3] years; 49.1 % female) were included. Median MCF was 27.0 % (21.8-32.8 %) for the overall group and was not different in the spironolactone and placebo groups. Over a median follow-up of 3.0 (1.9-4.5) years, MCF below median was associated with a worse prognosis (p = 0.003). On multivariable regression analysis (HR, 95 % CI), only New York Heart Association class (1.47, 1.14-1.91, p = 0.003) and MCF (0.76, 0.64-0.90, p = 0.001) were associated with the composite outcome. In this subset, spironolactone as compared to placebo was not associated with improved outcomes, but stratifying by MCF showed differential outcomes to spironolactone therapy (p = 0.010).

CONCLUSIONS

Among patients with HFpEF enrolled in TOPCAT, reduced MCF was independently associated with worse outcomes. Larger prospectively designed studies are needed to further assess the role of MCF in patients with HFpEF.

Potential Hematopoietic Effects of SGLT2 Inhibitors in Patients with Cardiac Amyloidosis

Background

Sodium-glucose cotransporter 2 inhibitors (SGLT2i) have been found to have potential hematopoietic effects in patients with heart failure (HF). However, these benefits have not been studied in patients with cardiac amyloidosis (CA). CA patients present with HF symptoms and often suffer from iron deficiency, which has a negative impact on erythropoiesis and leads to lower hemoglobin and hematocrit levels. We sought to determine the potential effects of SGLT2i on hematological parameters and functional capacity (FC) in CA patients.

Methods

A prospective analysis was conducted to compare the effects of SGLT2i in patients who received the best medical therapy (BMT) along with SGLT2i (n = 20), versus patients receiving only BMT without SGLT2i (n = 20) (historical control group). All patients underwent blood testing and cardiopulmonary exercise testing (CPET) at baseline (BL) and after 6 months [interquartile range (IQR): 4.0 to 8.0].

Results

The SGLT2i-based therapy resulted in a significant improvement and difference in hematological parameters at 6 months follow-up compared to the control group. In the SGLT2i group, the mean hemoglobin level increased (+1.2 mg/dL), whereas in the control group, it decreased (-0.8 g/dL) (p < 0.001 for overall group comparison). The hematocrit showed a significant increase in the SGLT2i group (+4.4%) compared to a decrease in the control group (-1.8%) (p < 0.001). Additionally, the serum iron level improved in the SGLT2i-treated group (+ 5.5 [-5.0 to 17.5] μg/dL vs. -6.0 [-15.0 to 4.0] μg/dL, p = 0.121). Although there was no significant change in the peak oxygen consumption (peak VO2, (mL/min)/kg) (p = 0.206), as well as in pulmonary ventilation (VE)/carbon dioxide production (VCO2) slope in both groups (p = 0.964), the SGLT2i group maintained a peak VO2 and VE/VCO2 slope throughout the study.

Conclusions

SGLT2i therapy improved hematological parameters and stabilized the FC of CA patients.

The Complex Puzzle of Hypertrophic Phenotype: A Practical Approach for the Clinician

Left ventricular hypertrophy (LVH) represents a frequent observation in clinical practice. Nonetheless, the hypertrophic phenotype emerges as a common manifestation of diverse conditions, thereby presenting a diagnostic conundrum for clinicians. Differentiation among the etiologies of LVH is imperative for therapy decision-making, as different approaches must be implemented for distinct conditions, such as LVH secondary to loading changes, hypertrophic cardiomyopathy (HCM), or HCM mimics. In some instances, an erroneous or late diagnosis may lead to a progression of the underlying disease with worsening functional capacity, high morbidity and mortality. The rational use of cardiovascular multimodality imaging is of great importance when carried out in addition to a thorough clinical assessment and correlated with electrocardiographic findings, providing clues to fill the gaps, being, most of the time, the missing piece to solve this challenging puzzle. An integrative approach is of paramount importance for the evaluation of these patients, as they are often followed by several specialties, with varied systemic manifestations. Although a multidisciplinary team is needed for an optimized follow-up of these patients, the most important player in this journey is the clinician, whose mission is to bring together all the red flags and coordinate all the data for an assertive diagnosis. The objective of this review is to provide a pragmatic methodology, highlighting important clues for discriminating among the diverse conditions that result in LVH.

Current Therapies and Future Horizons in Cardiac Amyloidosis Treatment

PURPOSE OF REVIEW

Cardiac amyloidosis (CA) is a condition characterized by misfolding and extracellular deposition of proteins, leading to organ dysfunction. While numerous forms of CA exist, two subtypes dominate clinical prevalence: Transthyretin amyloid (ATTR) and immunoglobulin light chain amyloid.

RECENT FINDINGS

The current scientific landscape reflects the urgency to advance therapeutic interventions with over 100 ongoing clinical trials. Heart failure treatment is affected by CA phenotype with poor tolerance of otherwise frequently used medications. Treating comorbidities including atrial fibrillation and valvular disease remains a challenge in CA, driven by technical difficulties and uncertain outcomes. Tafamidis is the first ATTR-stabilizer approved with a rapidly growing rate of clinical use. In parallel, various new therapeutic classes are in late-stage clinical trials including silencers, antibodies and genetic therapy. Managing CA is a critical challenge for future heart failure care. This review delineates the current standard-of-care and scientific landscape of CA therapy.

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.

Impact of vutrisiran on exploratory cardiac parameters in hereditary transthyretin-mediated amyloidosis with polyneuropathy

AIMS

HELIOS-A was a Phase 3, open-label study of vutrisiran, an RNA interference therapeutic, in patients with hereditary transthyretin (ATTRv) amyloidosis with polyneuropathy. This analysis evaluated vutrisiran's impact on exploratory cardiac endpoints in HELIOS-A patients.

METHODS AND RESULTS

Patients were randomized 3:1 to subcutaneous vutrisiran 25 mg every 3 months or intravenous patisiran 0.3 mg/kg every 3 weeks (reference group) for 18 months. Exploratory cardiac endpoints included change from baseline in N-terminal prohormone of brain-type natriuretic peptide (NT-proBNP) and echocardiographic parameters versus external placebo (APOLLO study). The modified intent-to-treat (mITT) population comprised randomized patients receiving any study drug (n = 122). A cardiac subpopulation with evidence of cardiac amyloid involvement (n = 40) was prespecified. 99mTc scintigraphy exploratory assessments in a planned vutrisiran-treated cohort at select sites were compared with baseline. At Month 18, vutrisiran demonstrated beneficial effects on NT-proBNP versus external placebo in the mITT and cardiac subpopulations (adjusted geometric mean fold change ratio [95% confidence interval] 0.480 [0.383-0.600], p = 9.606 × 10-10 and 0.491 [0.337-0.716], p = 0.0004, respectively). Benefits or trends towards benefit in echocardiographic parameters versus external placebo were observed for both populations. In 99mTc scintigraphy assessments, 32/47 (68.1%) and 31/48 (64.6%) patients exhibited reduced normalized left ventricular total uptake and heart-to-contralateral lung ratio, respectively. Perugini grade was reduced or unchanged versus baseline in 55/57 (96.5%) evaluable patients. No increase in cardiac adverse events was observed with vutrisiran versus external placebo.

CONCLUSIONS

Vutrisiran demonstrated evidence of potential benefit on cardiac manifestations in patients with ATTRv amyloidosis with polyneuropathy, with an acceptable safety profile.