Background: Cardiac
amyloidosis (CA) is a progressive infiltrative cardiomyopathy that leads to
severe heart failure. There are two leading pathogenetic causes (light
chains, AL-CA and ATTR-CA).
CA is underdiagnosed due to diagnostic challenging work up and
more importantly, missing awareness of health care professionals for this
disease. Beyond the need of
epidemiological data, diagnostic pathways have to be refined since novel
therapies are now available.
Aim: We aimed
to verify currently discussed disease surrogates, and
evaluate suggested and possible novel echocardiography parameters in a
population of patients with proven and suspicious CA.
Methods: A retro- and prospective database over an 8.5
year period (03/2009 and 09/2021) was established. During this time, 41,375
cardiac and non-cardiac patients underwent at least one echo exam for a broad
indication at our echo lab of a maximum care hospital. Patients with
suspicious echocardiograms were selected. Clinical
and laboratory parameters, comorbidities, ECG and echo data were collected for
all CA suspected cases. Comprehensive re-analysis of echo studies were done with
TomTec®-software including measurements of cavities, wall dimensions, functional
parameters, diastolic function and strain analysis among others.
Results:
While 128 patients were suspected, the
diagnosis was falsified in 16 and proven in 47 patients (Light chain n=16, ATTR
n= 31). During the aforementioned time frame of 101 months, we saw an incidence
of suspicious echocardiography of 1 per 328 patients (or 31 per 10,000), and an
incidence of proven cases of 1 per 880 echo patients (or 11.3 per 10,000). The
baseline characteristics show an overrepresented male sex (78,8%) and highly
overrepresented comorbidities as shown in table 1. As discussed in several
papers and position statements ([1], [2], [3], [4]) cardiac biomarkers were
severely elevated (table 1), whereas we saw a low voltage pattern in roughly
half of the patients (22 of 43 patients;
cut off: ≤0,5mV in limb leads). Echocardiographic parameters (table 2 and 3) are
in line with proposed CA-parameters, such as thickened walls (especially septum
wall), dilated atriums and an only slightly reduced LVEF. Our novel parameter “diastolic
thickness of the free right ventricular wall” (RVfWd), examined in the
subxiphoid view, is with a mean of 8,4 ± 1,9 mm highly pathologic (reference value: 3-5mm)
in our patient cohort, and represents the infiltration of both ventricles. Comparing
the specific indices with the current scientific evidence as shown in table 3,
we see severely impaired longitudinal strain while the circumferential strain remains
unimpaired, as known. The shown ratios (RWT, LVMI, MCF, EFSR and SVI) of our cohort
are in excellent agreement with the comparator groups from the literature. Also,
the modified RAISE- score [4] was applied by using the cut- off values of local
assays for troponin. Our cohort had a mean mRAISE-score of 3.0 ± 1.6 (range: 1 to 7), and therefore a high specificity and sensitivity
for CA.
Conclusion:
Echocardiography is a
useful tool for identifying CA patients undergoing echo examination for all
indications. Non-invasive diagnosis of advanced CA can mostly be established by
combining echocardiographic surrogates as well as clinical
and laboratory parameters.
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