SCIENTIFIC ARTICLE
Senile Cardiac Amyloidosis Presenting as Tachycardiainduced Cardiomyopathy : Case Report and Literature Review
Ajoe John Kattoor , MD ; Annette Abraham , MBBS ; Srikanth Vallurupalli , MD ; Hakan Paydak , MD Division of Internal Medicine and Division of Cardiology , UAMS , Little Rock
Abstract
Wild type transthyretin ( AT- TRwt ) cardiac amyloidosis , or senile cardiac amyloidosis , is an underdiagnosed disease . Data from autopsy studies show that , around one-fourth of elderly patients > 80 years has ATTRwt deposits in their heart . They often present with heart failure with or without conduction abnormalities . Atrial fibrillation is present in around 50 % of these patients and the risk of intra-atrial thrombus may be higher . We present the case of a 72-year-old man who presented with tachycardia mediated cardiomyopathy and was found to have ATTRwt amyloidosis .
Figure 1 : 2D echo image ( left ) and longitudinal strain image ( right ) showing increased wall thickness and apical sparing respectively , consistent with amyloidosis .
Case Presentation
Seventy-two-year-old African American male with no major medical illness presented to the hospital with palpitations and worsening dyspnea on exertion for the past six months . He denied chest pain , fever , chills , or dizziness . He was on no prescription medication at home and denied alcohol or drug abuse . At presentation , his heart rate was 115 bpm , blood pressure 125 / 82mmHg , and he was saturating normally on room air . Physical exam was significant for irregularly irregular rhythm with no signs of congestive heart failure ( CHF ).
Complete blood count , metabolic panel including liver function test , and thyroid function tests were normal . ECG showed atrial fibrillation with rapid ventricular rate , non specific T-wave abnormality in the inferolateral leads , and normal QRS voltage . Chest radiography showed mild cardiomegaly without any signs of overt heart failure . His prior workup for dyspnea included normal pulmonary function tests . A transthoracic echocardiogram revealed concentric left ventricular hypertrophy and reduced LV ejection fraction 25-30 %. Tachycardiamediated cardiomyopathy ( TCM ) was suspected and rhythm control by electrical cardioversion was planned . However , trans-esophageal echocardiography showed a 10mm X 10mm thrombus in the left atrial appendage . There was also evidence of spontaneous echo contrast (“ smoke ”). Due to the presence of atrial thrombus , the plan for cardioversion was abandoned . Patient was started on diuretics , long-acting metoprolol succinate and digoxin for rate control as well as warfarin for anticoagulation . Coronary angiography showed no obstructive coronary artery disease .
A month later , he was re-evaluated and found to have achieved sinus rhythm spontaneously . Medical management was continued and he was placed on amiodarone to keep him in sinus rhythm . A repeat echocardiogram revealed improvement in LV ejection fraction to 55 %. Wall thickness was increased ( septal wall thickness 2.2cm ) with grade 2 diastolic dysfunction and longitudinal strain analysis was suspicious for amyloidosis . Cardiac MRI was performed and confirmed concentric hypertrophy with a diffuse subendocardial enhancement pattern that did not confirm to a vascular territory ; the pattern was suspicious for cardiac amyloidosis .
Workup for AL amyloidosis including bone marrow aspirate and biopsy were negative for plasma cell neoplasm . To establish the diagnosis as well as determine the type of amyloid deposition , endomyocardial biopsy was performed . There was amyloid deposition in multiple foci in the interstitium and vessel walls of heart confirmed by thioflavin-t and Congo red stains . Mass spectrometry for amyloid subtyping resulted in transthyretin wild type amyloid . Sequencing of the TTR gene did not show a known mutation .
Follow up and outcome
The patient was started on diflunisal therapy to prevent further aggregation of transthyretin molecules . One year post-diagnosis patient continues to have signs and symptoms of fluid overload , currently being managed with increasing doses of diuretics and paracentesis . His atrial fibrillation did not recur and he continues to be on amiodarone therapy .
Discussion
This previously asymptomatic patient with no prior co-morbidities presented with atrial fibrillation and LV systolic dysfunction . It was attributed to tachycardia mediated cardiomyopathy and improved with rhythm control therapy . However ,
66 • THE JOURNAL OF THE ARKANSAS MEDICAL SOCIETY VOLUME 115