Results of a Screening Program for Diagnosis of Amyloid Cardiomyopathy Among Patients with Left Ventricular Hypertrophy: PAPCAT Cardiac Amyloidosis Türkiye Survey.

BACKGROUND

Cardiac amyloidosis (CA) is an increasingly recognized disease. Several recent advanced imaging techniques and parameters have been introduced into the diagnosis of CA. However, the first step in using those techniques is clinical suspicion. Left ventricular hypertrophy (LVH) is the main entity in rising the suspicion of CA in routine echocardiography, although it is not a diagnosis for CA. The aim of this study is to investigate the prevalence of CA and its subtypes and predictive value of clinical and echocardiographic red flags of CA among consecutive adult patients with LVH identified during routine echocardiographic examination in 25 tertiary institutions in Türkiye.

METHODS

This was a prospective observational multicenter, national registration study. Patients with LVH (interventricular septum thickness ≥13 mm or >15 mm in those with hypertension) were screened for CA stepwise. The first step was a clinical questionnaire for the red flags of CA. Those having ≥2 red flags were further analyzed by detailed echocardiography, blood tests, Tc-pyrophosphate (PYP) bone scintigraphy, and histopathological examination if needed. Parameters associated with CA were evaluated via univariate and multivariate analyses. Wild-type transthyretin (wTTR) vs. mutant-type TTR (mTTR), CA discriminators were also evaluated in the same manner.

RESULTS

A total of 420 patients meeting these criteria were included in the study. With a standardized algorithmic approach, 27.1% (114) of patients received a CA diagnosis. Among these patients with CA, 50.8% (58) were diagnosed with immunoglobulin free chain (AL) CA, 38.6% (44) with wTTR CA, and 7% (8) with mTTR CA. Left ventricular apical sparing pattern and restrictive type LV filling on echocardiography, low QRS voltage on ECG, bilateral carpal tunnel syndrome, low blood pressure, right ventricular diameter, and an increased basal heart rate (HR) were independent predictors for CA diagnosis. When it comes to diagnosis of wTTR CA; advanced age (age >75), lower troponin values, absence of pericardial effusion and absence of proteinuria were the independent predictors.

CONCLUSION

Cardiac amyloidosis is highly prevalent in a patient population with LVH and 2 red flags who underwent a standardized algorithmic approach, in which apical sparing, restrictive filling pattern, low QRS voltage, carpal tunnel syndrome, low blood pressure, and increased HR are the highly suggestive signs of CA. Among this pool of newly diagnosed CA patients in Türkiye, AL-CA constituted 50.8%, wTTR CA 38.6%, and mTTR CA 7%, emphasizing that approximately 1 in 2 patients diagnosed with CA may have TTR CA.