Case History
A 78-year-old Caucasian male with a past medical history significant for chronic diastolic heart failure with preserved ejection fraction (HfpEF), atrial fibrillation status post pulmonary vein isolation 8 years ago and extensive circumferential ablation for recurrent atrial fibrillation 6 years ago, as well as cavo-isthmus ablation with bidirectional block for atypical atrial flutter with recurrence of atrial flutter 5 years ago presented with increasing dyspnea and palpitations. Flecainide and Diltiazem had been discontinued due to side effects and renal impairment.
There was discordance between QRS voltage on ECG and the degree of left ventricular (LV) wall thickness on echocardiogram (Figure 1B, 1C, 1D), leading to suspicion for. infiltrative cardiomyopathy, subsequently confirmed as Transthyretin type type cardiac amyloidosis and confirmed on two-dimensional speckle-tracking echocardiography (2D-STE) and cardiac magnetic resonance imaging (MRI). Serum light chains were both slightly elevated but with normal ratio. STE revealed abnormal global averaged LV longitudinal peak systolic strain of -8 % (normal = more negative than -18%, Figure 2A), and prominent apical sparing pattern suggestive of cardiac amyloidosis (Figure 2B). MRI showed significantly increased left ventricular wall thickness, diffuse subendocardial, predominantly late, gadolinium enhancement and preserved LV function, ejection fraction of 59% and normal LV volumes. Right ventricular (RV) volumes were preserved with mild systolic dysfunction and RV ejection fraction of 41%. Late gadolinium enhanced sequences demonstrated global predominantly subendocardial but some areas of transmural late gadolinium enhancement Enhancement also extended to the atrial walls, left greater than right, with mild thickening of the interatrial septum (Figure 2C). Pre-contrast T1 mapping value was significantly elevated at greater than 1300 ms (normal 1020 ms, Figure 2D). Findings were consistent with cardiac amyloidosis. Patient was started on Tafamadis, underwent transesophageal echocardiography (TEE) guided cardioversion and was discharged.
Two months later patient was admitted for recurrent progressive exertional dyspnea and palpitations with ECG similar to prior admission 2 months ago showing atypical slow atrial flutter with 2:1 block and left bundle branch block (Figure 1A).  Heart rate was 90 beats/minute and blood pressure was 120/86 mm Hg.  Chest x-ray did not show any acute cardiopulmonary process. INR was 2.0, serum potassium was 5.3 mEq/L, serum creatinine was 1.76 mg/dL, serum magnesium was 2.4 mg/dL, and NT-Pro BNP was 4335 pg/mL (normal ≤ 77). Medications included apixaban 5 mg bid, spironolactone 25 mg qd, tafamidis 61 mg qd and tramadol 50 mg qd. He was initiated on amiodarone 100 mg bid and furosemide diuresis and referred for TEE-guided cardioversion. TEE identified no left or right atrial appendage thrombus, mild MR and trace TR. TEE probe was left in situ during cardioversion to assess left atrial (LA) appendage post cardioversion, due to post cardioversion atrial stunning, and higher risk of thrombus formation in cardiac amyloid. Patient was successfully cardioverted at first attempt with return to normal sinus rhythm (Figure 3). TEE demonstrated LVEF of 38% prior to, and 41% following cardioversion. Pre-cardioversion TEE pulsed wave PW Doppler (PW) of the right atrial appendage showed regular Doppler velocities corresponding to each flutter wave on the ECG but with reduced amplitude of every alternate appendage velocity (Figure 4A). Doppler velocity returned to normal pattern post-cardioversion (Figure 4B). RA appendage velocities were normal in amplitude post cardioversion. LA appendage flow velocities showed similar pattern with alternate smaller amplitude PW Doppler velocities corresponding to every alternate flutter wave (Figure 4C), with return to normal pattern but with reduced velocities post-cardioversion (Figure 4D). Mitral inflow PW Doppler showed a single early filling wave with an indiscernible A wave pre cardioversion (Figure 4E). which reverted to E and A fusion pattern post cardioversion due to the presence of first-degree AV block (Figure 4F). Tricuspid annular tissue Doppler imaging pre cardioversion showed two additional velocities, one with smaller amplitude preceding and one with larger amplitude following annular e’ wave, both immediately following the flutter P wave on the ECG prior to cardioversion (Figure 5A). These waves disappeared during sinus rhythm with good amplitude tissue Doppler a’ wave suggesting good right atrial function after cardioversion (Figure 5B). These velocities were almost unrecognizable on mitral inferolateral annular Doppler pre cardioversion (Figure 5C) and normal tissue Doppler mitral annular pattern emergent post cardioversion (Figure 5D).
Other pre cardioversion TEE findings included restrictive appearing mitral inflow pattern (Figure 5E) and increased TR peak velocity at 3.1 m/sec corresponding to a pressure gradient of 38 mm Hg and consistent with LV diastolic dysfunction and pulmonary venous hypertension. He remained in normal sinus rhythm and discharged the following day. Five months later, the patient underwent dual-chamber biventricular pacemaker implantation with the coronary sinus lead placed into a lateral branch of the coronary sinus.  He underwent AV nodal ablation three months after the implantation of the pacemaker. ECG post AV nodal ablation showed biventricular pacing at 70 bpm with underlying slow atrial flutter (Figure 6).