Myocardial structural and functional changes in cardiac amyloidosis: insights from a prospective observational patient registry

AIMS

The pathophysiological hallmark of cardiac amyloidosis (CA) is the deposition of amyloid within the myocardium. Consequently, extracellular volume (ECV) of affected patients increases. However, studies on ECV progression over time are lacking. We aimed to investigate the progression of ECV and its prognostic impact in CA patients.

METHODS AND RESULTS

Serial cardiac magnetic resonance (CMR) examinations, including ECV quantification, were performed in consecutive CA patients. Between 2012 and 2021, 103 CA patients underwent baseline and follow-up CMR, including ECV quantification. Median ECVs at baseline of the total (n = 103), transthyretin [(ATTR) n = 80], and [light chain (AL) n = 23] CA cohorts were 48.0%, 49.0%, and 42.6%, respectively. During a median period of 12 months, ECV increased significantly in all cohorts [change (Δ) +3.5% interquartile range (IQR): -1.9 to +6.9, P < 0.001; Δ +3.5%, IQR: -2.0 to +6.7, P < 0.001; and Δ +3.5%, IQR: -1.6 to +9.1, P = 0.026]. Separate analyses for treatment-naïve (n = 21) and treated (n = 59) ATTR patients revealed that the median change of ECV from baseline to follow-up was significantly higher among untreated patients (+5.7% vs. +2.3%, P = 0.004). Survival analyses demonstrated that median change of ECV was a predictor of outcome [total: hazard ratio (HR): 1.095, 95% confidence interval (CI): 1.047-1.0145, P < 0.001; ATTR: HR: 1.073, 95% CI: 1.015-1.134, P = 0.013; and AL: HR: 1.131, 95% CI: 1.041-1.228, P = 0.003].

CONCLUSION

The present study supports the use of serial ECV quantification in CA patients, as change of ECV was a predictor of outcome and could provide information in the evaluation of amyloid-specific treatments.

Monitoring tafamidis treatment with quantitative SPECT/CT in transthyretin amyloid cardiomyopathy

AIMS

Tafamidis treatment positively affects left ventricular (LV) structure and function and improves outcomes in patients with transthyretin amyloid cardiomyopathy (ATTR-CM). We aimed to investigate the relationship between treatment response and cardiac amyloid burden identified by serial quantitative 99mTc-DPD SPECT/CT. We furthermore aimed to identify nuclear imaging biomarkers that could be used to quantify and monitor response to tafamidis therapy.

METHODS AND RESULTS

Forty wild-type ATTR-CM patients who underwent 99mTc-DPD scintigraphy and SPECT/CT imaging at baseline and after treatment with tafamidis 61 mg once daily [median, 9.0 months (interquartile range 7.0-10.0)] were divided into two cohorts based on the median (-32.3%) of the longitudinal percent change in standardized uptake value (SUV) retention index. ATTR-CM patients with a reduction greater than or equal to the median (n = 20) had a significant decrease in SUV retention index (P < 0.001) at follow-up, which translated into significant benefits in serum N-terminal prohormone of brain natriuretic peptide levels (P = 0.006), left atrial volume index (P = 0.038), as well as LV [LV global longitudinal strain: P = 0.028, LV ejection fraction (EF): P = 0.027, LV cardiac index (CI): P = 0.034] and right ventricular (RV) [RVEF: P = 0.025, RVCI: P = 0.048] functions compared with patients with a decrease less than the median (n = 20).

CONCLUSION

Treatment with tafamidis in ATTR-CM patients results in a significant reduction in SUV retention index, associated with significant benefits for LV and RV function and cardiac biomarkers. Serial quantitative 99mTc-DPD SPECT/CT imaging with SUV may be a valid tool to quantify and monitor response to tafamidis treatment in affected patients.

TRANSLATIONAL PERSPECTIVE

99mTc-DPD SPECT/CT imaging with determination of SUV retention index as part of a routine annual examination can provide evidence of treatment response in ATTR-CM patients receiving disease-modifying therapy. Further long-term studies with 99mTc-DPD SPECT/CT imaging may help to evaluate the relationship between tafamidis-induced reduction in SUV retention index and outcome in patients with ATTR-CM and will demonstrate whether highly disease-specific 99mTc-DPD SPECT/CT imaging is more sensitive than routine diagnostic monitoring.

Impact of tafamidis on myocardial strain in transthyretin amyloid cardiomyopathy

AIMS

The impact of tafamidis on myocardial strain in patients with transthyretin amyloid cardiomyopathy (ATTR-CM) have been barely investigated. We aimed to determine tafamidis-induced changes using serial speckle tracking echocardiography and to identify imaging parameters for specific therapy monitoring.

METHODS AND RESULTS

ATTR-CM patients underwent serial TTE with two-dimensional (2 D) speckle tracking imaging. Patients receiving tafamidis free acid 61 mg (n = 62) or tafamidis meglumine 20 mg (n = 21) once daily (QD) showed stable measurements at follow-up (61 mg: 8.5 months, 20 mg: 7.0 months) in LV global longitudinal strain (GLS) (61 mg: -11.75% vs. -11.58%, p = 0.534; 20 mg: -10.61% vs. -10.12%, p = 0.309), right ventricular (RV) GLS (61 mg: -14.18% vs. -13.72%, p = 0.377; 20 mg: -14.53% vs. -13.99%, p = 0.452) and left atrial (LA) reservoir strain (LASr; 61 mg: 8.80% vs. 9.42%, p = 0.283; 20 mg: 8.23% vs. 8.67%, p = 0.589), whereas treatment-naïve ATTR-CM patients (n = 54) had clear signs of disease progression at the end of the observation period (10.5 months; LV-GLS: -11.71% vs. -10.59%, p = 0.001; RV-GLS: -14.36% vs. -12.99%, p = 0.038; LASr: 10.67% vs. 8.41%, p = 0.005). Between-group comparison at follow-up revealed beneficial effects of tafamidis free acid 61 mg on LASr (p = 0.003) and the LV (LV-GLS: p = 0.030, interventricular septum (IVS): p = 0.006), resulting in clinical benefits (six-minute walk distance (6-MWD): p = 0.006, NT-proBNP: p= <0.001), while patients treated with tafamidis meglumine 20 mg QD showed positive effects on LASr (p = 0.039), but no differences with respect to the LV (LV-GLS: p = 0.274, IVS: p = 0.068) and clinical status (6-MWD: p = 0.124, NT-proBNP: p = 0.053) compared to the natural course.

CONCLUSIONS

Treatment with tafamidis free acid 61 mg in ATTR-CM patients delays the deterioration of LA and LV longitudinal function, resulting in significant clinical benefits compared with natural history. Serial TTE with 2 D speckle tracking imaging may be appropriate for disease-specific therapy monitoring.

Two-dimensional speckle-tracking echocardiography in tafamidis-treated patients with transthyretin amyloid cardiomyopathy: a glimmer of hope for viable therapy monitoring?

Background

Treatment with Tafamidis in patients with transthyretin amyloid cardiomyopathy (ATTR-CM) has been shown to have beneficial effects on the left ventricle (LV), as assessed by cardiac magnetic resonance (CMR) imaging. Although CMR represents the gold standard among imaging modalities, its limited availability in clinical practice makes it unfeasible for routine therapy monitoring.

Purpose

We aimed to determine Tafamidis-induced changes using two-dimensional (2D) speckle-tracking echocardiography and to identify echocardiographic imaging parameters that could be used for specific therapy monitoring.

Methods

We subjected a series of ATTR-CM patients to transthoracic echocardiography (TTE) at baseline and follow-up and compared patients treated with Tafamidis 61mg once daily (QD) to a historical control cohort treated with Tafamidis 20mg QD, as well as to a historical treatment-naïve control cohort reflecting the natural course of the disease.

Results

Patients receiving Tafamidis 61mg (n=62) or 20mg (n=21) QD showed stable measurements at follow-up [61mg: 8.5 months, 20mg: 7.0 months] in LV global longitudinal strain (GLS) (61mg: −11.75% vs. −11.58%, p=0.534; 20mg: −10.61% vs. −10.12%, p=0.309), right ventricular (RV) GLS (61mg: −14.18% vs. −13.72%, p=0.377; 20mg: −14.53% vs. −13.99%, p=0.452) and left atrial (LA) reservoir strain (LASr; 61mg: 8.80% vs. 9.42%, p=0.283; 20mg: 8.23% vs. 8.67%, p=0.589), whereas treatment-naïve ATTR-CM patients (n=54) had clear signs of disease progression at the end of the observation period [10.5 months; LV-GLS: −11.71% vs. −10.59%, p=0.001; RV-GLS: −14.36% vs. −12.99%, p=0.038; LASr: 10.67% vs. 8.41%, p=0.005]. Between-group comparison at follow-up revealed beneficial effects of Tafamidis 61mg on LASr (p=0.003), LV-GLS (p=0.030) and interventricular septum (IVS) thickness (p=0.006), resulting in clinical benefits (six-minute walk distance (6-MWD): p=0.006, NT-proBNP: p≤0.001), while patients treated with Tafamidis 20mg QD showed positive effects on LASr (p=0.039) but no differences in LV-GLS (p=0.274), IVS thickness (p=0.068) and clinical status (6-MWD: p=0.124, NT-proBNP: p=0.053) compared to the natural course.

Conclusion

Treatment with Tafamidis 61mg in ATTR-CM patients delays the increase in IVS thickness and the deterioration of LA and LV longitudinal function, resulting in significant clinical benefits compared with natural history. Serial TTE with 2D speckle-tracking imaging may be appropriate for disease-specific therapy monitoring.

Funding Acknowledgement

Type of funding sources: Private company. Main funding source(s): This work was supported by the Pfizer Inc. However, Pfizer Inc. did not have influence on study design, data processing, or statistical analysis.