Atrial enhancement by cardiovascular magnetic resonance in cardiac amyloidosis

Atrial Fibrillation in Patients with Hypertrophic Cardiomyopathy and Cardiac Amyloidosis: From Clinical Management to Catheter Ablation Indication

Atrial fibrillation (AF) is the most common arrhythmia in patients affected by cardiomyopathies. Reports estimate a prevalence of 27% in patients with hypertrophic cardiomyopathy (HCM) and 40% in patients with cardiac amyloidosis (CA). The presence of AF typically results in progressive functional decline, an increased frequency of hospitalizations for heart failure, and a higher thromboembolic risk. Medical management using mainly beta-blockers or amiodarone has produced variable outcomes and a high rate of recurrence. Catheter ablation reduces symptom burden and complications despite a moderate rate of recurrence. Recent evidence suggests that an early rhythm control strategy may lead to more favorable short- and long-term outcomes. In this review, we summarize contemporary data on the management of AF in patients with cardiomyopathy (HCM and CA) with particular reference to the timing and outcomes of ablation procedures.

Atrial amyloidosis: mechanisms and clinical manifestations

Cardiac amyloidosis (CA) is now recognized as an important cause of heart failure. Increased wall thickness and diastolic dysfunction of the left ventricle are the most easily detectable manifestations of CA, but amyloid accumulates in all cardiac structures. Involvement of the left and right atria may be due to the haemodynamic effects of ventricular diastolic dysfunction, the effects of amyloid infiltration into the atrial wall, and the cardiotoxic damage of atrial cardiomyocytes by amyloid precursors. Atrial amyloidosis is an early manifestation of CA, and is associated with an increased risk of atrial fibrillation and thromboembolic events. Furthermore, atrial amyloidosis can be found even in the absence of systemic disease and ventricular involvement. This condition is named isolated atrial amyloidosis and is due to a local overproduction of atrial natriuretic peptide. In this review we summarize the evidence on the mechanisms and clinical relevance of atrial amyloidosis.

Restricted left atrial dilatation can visually differentiate cardiac amyloidosis from hypertrophic cardiomyopathy

Aims

Cardiac amyloidosis (CA) is an infiltrative myocardial disease that occasionally mimics hypertrophic cardiomyopathy (HCM). The aim of this study is to investigate the discriminatory ability of visual assessment of left atrial (LA) function between CA and HCM on echocardiography.

Methods and results

In total, 93 patients with cardiac magnetic resonance imaging (CMR)‐confirmed HCM and 34 with cardiac biopsy‐confirmed CA were retrospectively assessed. LA dilatation was assessed via echocardiography in an apical four‐chamber view. Visual assessment was performed to identify LA dilatation grade (preserved = 1, abnormal = 2, and restricted = 3) based on the extent of outward expansion in the LA reservoir phase. Regarding the reproducibility of visually assessing LA dilatation grade, the kappa values between intra‐ and inter‐observer measurements were 0.82 and 0.70, respectively. Of 127 participants, 57 (45%), 42 (33%), and 28 (22%) presented with LA dilatation Grades 1, 2, and 3, respectively. All 57 patients with preserved LA dilatation (Grade 1) had HCM, and 20 of 28 patients (71%) with restricted LA dilatation (Grade 3) presented with CA. Patients with CA had a higher LA dilatation grade than those with HCM (P < 0.01). LA emptying fraction and reservoir strain were also quantitatively evaluated. The area under the curves of LA dilatation grade (0.88) and LA emptying fraction (0.88) for differentiation of these two diseases were higher than that of LA reservoir strain (0.73) (P < 0.01, respectively). During follow‐up, nine patients with HCM and 16 with CA experienced cardiac event (cardiac death or hospitalization due to heart failure). In Kaplan–Meier analysis including both groups of HCM and CA, the incidence of cardiac events was higher in patients with restricted LA dilatation than in those with preserved or abnormal LA dilatation (log‐rank test, P < 0.01).

Conclusions

Restricted LA dilatation is an indicator for the diagnosis of CA. Further, visual assessment of abnormal LA motion may facilitate diagnosis in patients with CA and high‐risk patients with HCM.

Heart failure with preserved ejection fraction, atrial fibrillation, and the role of senile amyloidosis

Heart failure with preserved ejection fraction (HFpEF) and atrial fibrillation (AF) are very common conditions, particularly in the elderly. However, the mechanisms underlying the two disorders, including their intricate interaction have not been fully resolved. Here, our aim is to review the evidence on the role of the two types of senile amyloidosis in this connection. Two types of senile amyloidosis can be identified: wild-type transthyretin (TTR)-derived amyloidosis (ATTRwt) and isolated atrial amyloidosis (IAA). ATTRwt is an underlying condition that is being increasingly recognized in patients with HFpEF and often accompanied by AF. IAA is an established cause of AF, adding to the mechanism problem. New diagnostic and therapeutic possibilities have emerged that may facilitate clinical management of (senile) amyloidosis, which in turn may have implications for the management of HFpEF and AF.

Restrictive Cardiomyopathies: The Importance of Noninvasive Cardiac Imaging Modalities in Diagnosis and Treatment-A Systematic Review

Restrictive cardiomyopathy (RCM) is the least common among cardiomyopathies. It can be idiopathic, familial, or secondary to systematic disorders. Marked increase in left and/or right ventricular filling pressures causes symptoms and signs of congestive heart failure. Electrocardiographic findings are nonspecific and include atrioventricular conduction and QRS complex abnormalities and supraventricular and ventricular arrhythmias. Echocardiography and cardiac magnetic resonance (CMR) play a major role in diagnosis. Echocardiography reveals normal or hypertrophied ventricles, preserved systolic function, marked biatrial enlargement, and impaired diastolic function, often with restrictive filling pattern. CMR offering a higher spatial resolution than echocardiography can provide detailed information about anatomic structures, perfusion, ventricular function, and tissue characterization. CMR with late gadolinium enhancement (LGE) and novel approaches (myocardial mapping) can direct the diagnosis to specific subtypes of RCM, depending on the pattern of scar formation. When noninvasive studies have failed, endomyocardial biopsy is required. Differentiation between RCM and constrictive pericarditis (CP), nowadays by echocardiography, is important since both present as heart failure with normal-sized ventricles and preserved ejection fraction but CP can be treated by means of anti-inflammatory and surgical treatment, while the treatment options of RCM are dictated by the underlying condition. Prognosis is generally poor despite optimal medical treatment.

Characterization of Cardiac Amyloidosis by Atrial Late Gadolinium Enhancement Using Contrast-Enhanced Cardiac Magnetic Resonance Imaging and Correlation With Left Atrial Conduit and Contractile Function

The diagnosis of cardiac amyloidosis (CA) often necessitates invasive myocardial biopsy. We sought to evaluate whether late gadolinium enhancement (LGE) of the atrial myocardium by cardiac magnetic resonance imaging was associated with impaired left atrial (LA) function and whether the extent of LA LGE may enhance diagnostic differentiation of CA from other cardiomyopathies. Twenty-two patients with biopsy-proven CA, 37 with systemic hypertension (SH), and 22 with nonischemic dilated cardiomyopathy (NIDC) underwent cardiac magnetic resonance imaging and echocardiographic evaluation. Patients with CA had greater minimal LA volume (57 ± 53 vs 24 ± 18 in SH and 19 ± 25% in NIDC, p = 0.003), and significantly lower total LA emptying function (19 ± 14 vs 40 ± 14 in SH and 33 ± 20% in NIDC, p = 0.0006). The mean proportion of atrial enhancement (LGELA%) was significantly greater in patients with CA than with SH and NIDC (59 ± 36% vs 7.4 ± 2.1 and 2.9 ± 9.0%, p <0.0001, respectively). There was also a strong inverse correlation between both active and total atrial emptying (r = -0.69, p = 0.001; r = -0.67, p = 0.01, respectively) with LGELA% for patients with CA. In multivariate regression analysis, LGELA% was the strongest adjusted predictor for CA diagnosis. Using receiver operating characteristic analysis, LGELA% ≥33% produced the greatest diagnostic utility for CA (sensitivity 76%, specificity 94%). Patients with CA may have extensive LGE of the LA myocardium, which is associated with marked reduction in LA emptying function. The extent of LA LGE was highly predictive for the diagnosis of CA.

[MRI in cardiac sarcoidosis and amyloidosis]

CLINICAL/METHODICAL ISSUE

Sarcoidosis and amyloidosis are both multisystem disorders, which may involve the heart; however, isolated cardiac disease is rare. Diagnosis of cardiac sarcoidosis and amyloidosis is crucial because the patient prognosis is dependent on cardiac involvement and early treatment.

STANDARD RADIOLOGICAL METHODS

Echocardiography is the first line imaging modality in the diagnostic work-up of both diseases, possibly giving hints towards the correct diagnosis. Besides myocardial biopsy and radionuclide studies cardiac magnetic resonance imaging (MRI) is routinely performed in patients suspect of having infiltrative cardiomyopathy.

METHODICAL INNOVATIONS

The T1 mapping procedure is currently being evaluated as a new technique for detection and quantification of global myocardial enhancement, as seen in cardiac amyloidosis.

PERFORMANCE

Sensitivities and specificities for detection of cardiac sarcoidosis and amyloidosis can be significantly improved by MRI, especially with late gadolinium enhancement (LGE) imaging. In cardiac sarcoidosis the use of LGE is outcome-related while in amyloidosis analysis of T1-mapping may be of prognostic value.

PRACTICAL RECOMMENDATIONS

If cardiac involvement in sarcoidosis or amyloidosis is suspected cardiac MRI including LGE should be performed for establishing the diagnosis.

Prognostic impact of T2-weighted CMR imaging for cardiac amyloidosis

OBJECTIVES

Using cardiac magnetic resonance imaging (MRI) we tested the diagnostic value of various markers for amyloid infiltration.

METHODS

We performed MRI at 1.5 T in 36 consecutive patients with cardiac amyloidosis and 48 healthy volunteers. The protocol included cine imaging, T2-weighted spin echo, T1-weighted spin echo before and early after contrast and late gadolinium enhancement. We compared the frequency of abnormalities and their relation to mortality.

RESULTS

Median follow-up was 31 months. Twenty-three patients died. Mean left ventricular (LV) mass was 205 ± 70 g. LV ejection fraction (EF) was 55 ± 12%. T2 ratio was 1.5 ± 0.4. 33/36 patients had pericardial and 22/36 had pleural effusions. All but two had heterogeneous late enhancement. Surviving patients did not differ from those who had died with regard to gender, LV mass or volume. Surviving patients had a significantly higher LVEF (60.4 ± 9.9% vs. 51.6 ± 11.5%; p = 0.03). The deceased patients had a lower T2 ratio than those who survived (1.38 ± 0.42 vs. 1.76 ± 0.17; p = 0.005). Low T2 was associated with shorter survival (Chi-squared 11.3; p < 0.001). Cox regression analysis confirmed T2 ratio < 1.5 as the only independent predictors for survival.

CONCLUSION

Cardiac amyloidosis is associated with hypointense signal on T2-weighted images. A lower T2 ratio was independently associated with shortened survival.

MRI of cardiac involvement in transthyretin familial amyloid polyneuropathy

OBJECTIVE

The purpose of this study was to evaluate cardiac MRI features in a group of patients with transthyretin familial amyloid polyneuropathy (FAP).

SUBJECTS AND METHODS

Sixteen patients with transthyretin FAP underwent 2D echocardiography with Doppler examination, cardiac MRI, and (99m)Tc-diphosphonate (DPD) scintigraphy. Four patients had peripheral polyneuropathy, three had carpal tunnel syndrome, one patient had symptoms and signs of heart failure, and eight patients had no symptoms but had a family history of FAP. At MRI, cardiac function parameters and delayed contrast enhancement findings were evaluated.

RESULTS

Six patients had cardiac radiotracer uptake at scintigraphy (FAP cardiac group), and 10 patients had no cardiac uptake (FAP noncardiac group). The FAP cardiac group included the four patients with peripheral neuropathy, one patient with carpal tunnel syndrome, and the only patient with heart failure. At MRI, abnormal contrast enhancement was found in all patients with positive scintigraphic findings and in no patient with negative scintigraphic findings. All patients had involvement of the left ventricle and other chambers or structures (atria, right ventricle, tricuspid valve leaflets). Left ventricular contrast enhancement was focal in four patients, subendocardial circumferential in one patient, and diffuse in one patient. The only patient with signs of heart failure had circumferential subendocardial enhancement.

CONCLUSION

Cardiac contrast-enhanced MRI can be used to identify cardiac amyloidosis in patients with FAP who do not have clinical signs of heart involvement. In these patients, the typical subendocardial circumferential pattern of contrast enhancement is rare. We observed unusual enhancement patterns as focal or diffuse left ventricular enhancement accompanied by enhancement of the atria, tricuspid valve, or right ventricle.

Cardiac MRI evaluation of nonischemic cardiomyopathies

The purpose of this manuscript is to review the major MRI findings in patients with nonischemic cardiomyopathies. Cardiac MRI has become an integral part in the diagnosis and management of patients with nonischemic cardiomyopathies. Findings on cardiac MRI studies can help distinguish between different types of cardiomyopathies and can provide valuable diagnostic and prognostic information.