To estimate the prevalence of transthyretin cardiac amyloidosis (TTR-CA) among Heart Failure with Preserved Ejection Fraction (HFpEF) patients with increased LV wall thickness in Southeast Minnesota using 99mTc-PYP single-photon positive emission computed tomography with computed tomography (SPECT/CT).

Residents of Southeast Minnesota over 60 years of age with an inpatient or outpatient diagnosis of heart failure (HF) will be consecutively identified in real-time using a natural language processing (NLP) search engine, their HF diagnosis validated, and those with a recent (≤ 12 months) echocardiogram documenting a preserved EF( ≥ 40%) and LV wall thickening will be consented to undergo venipuncture, urine collection and 99mTc-PYP SPECT/CT imaging to rule in/out the diagnosis of TTR-CA. Hence, the prevalence of TTR-CA will be defined. To place this prevalence in perspective of the global HFpEF cohort in the community, a rigorous screening log will be maintained to allow generation of a comprehensive CONSORT diagram. Importantly, baseline characteristics of patients who qualify for our study but decline to consent will still be collected provided that consent for use of their records for medical research had previously been granted.

Inclusion Criteria

1. Resident of Southeastern Minnesota (Olmsted, Dodge, Fillmore, Mower, Freeborn, Wabasha, or Steele County)

2. Current diagnosis of HF per NLP search

3. Age > 60 years

4. Clinically obtained echocardiogram within 12 months of index visit showing:

   1. EF ≥ 40% and
   2. Increased Left Ventricular (LV) wall thickness as defined by an end-diastolic left ventricular septal or posterior wall thickness (LVWTd) ≥ 20% above the upper limit of normal measured by 2D or M-mode imaging in the parasternal long (2D) or short (M-mode) axis view (≥12 mm).

5. Objective evidence of HF defined as one or more of the following present within 24 months of index visit:

   1. Meet Framingham Criteria at index visit (In-patient or outpatient)
   2. Previous HF hospitalization
   3. Invasive hemodynamic documentation of elevated pulmonary capillary wedge pressure (PCWP) or left ventricular end-diastolic pressure (LVEDP) (> 18 mmHg at rest or > 25 mmHg with exercise)
   4. Left atrial enlargement + loop diuretic for HF(clinically obtained) N-terminal pro b-type natriuretic peptide (NT-proBNP) > 300 (sinus rhythm) or >900 (atrial fibrillation) pg/mL

Exclusion Criteria

1. Documentation of previous EF < 40%

2. Any cardiac surgery or major chest trauma within 4 weeks of index visit

3. Presence or history of hemodynamically significant left sided valvular disease defined as:

   1. Greater than mild mitral stenosis
   2. Intrinsic mitral valve disease (prolapse, flail) with greater than moderate regurgitation

4. Myocardial infarction within 4 weeks of index visit defined by typical angina, EKG changes and significant change in serial troponins. Note that chronic troponin elevation is extremely common in cardiac amyloidosis. Hospitalized patients with troponin elevation but no significant change (delta) on serial testing will NOT be excluded.

5. Prior or current exposure to Plaquenil (Hydroxychloroquine)