Scientific Concept of the National Cohort (status ... - Nationale Kohorte

A.3
A.3 Study design
index, conventional methods using oscillometric blood pressure measurement devices and
hand-held Doppler devices to detect systolic blood pressure at the brachial artery, the dorsal
artery of foot, and posterior tibial artery are available as well.
For the National Cohort, one of the multifunctional devices will be used. The potential of
the Vascular Explorer or the Vicorder device to replace the more observer-dependent and
time-consuming use of the Sphygmocor device in the National Cohort will be evaluated in
a feasibility study.
Carotid sonography: intima–media thickness
Atherosclerotic disease begins in early life, progresses over decades 581 , and may result
in rupture or erosion of existing plaques, leading to MI or stroke 582 . The degree of subclinical
atherosclerosis as defined by CIMT or presence of carotid plaques is a predictor
of incident CVD events in the absence of overt CVD 583-588 . Vascular imaging such as CIMT
measurements with B-mode ultrasound is a noninvasive, sensitive, and reproducible technique
for identifying and quantifying atherosclerotic burden and CVD risk and can be used
as a screening tool that improves risk prediction beyond application of major risk factors
alone 589-591 .
By including carotid ultrasound measures as a surrogate of subclinical atherosclerosis in
the examination protocol of the National Cohort we can compare our results with those of
other large-scale epidemiologic studies.
Procedure of measurement:
High-resolution B-mode ultrasound systems with linear ultrasound transducers (frequencies
≥ 7 MHz) represent the standard equipment for measuring CIMT and plaques. For the National
Cohort, a combined ultrasound system will be used for echocardiography and carotid
artery imaging. Examinations will be perfomed by trained and certified investigators and will
be done at both carotid arteries. External landmarks (e.g., the Meijer arc or similar devices)
will be used to standardize transducer angle. CIMT is measured preferably on the far wall
from multiple sequences of longitudinal scans of the common carotid artery. The reading
will be done offline using automated reading software. Carotid plaques will be evaluated at
the near and far walls of common carotid artery, bulb, and internal carotid artery segments.
Scanning and measurement procedures as well as definitions of CIMT and carotid plaques
will be in accordance with current guidelines 592, 593 .
long-term ECG recording and sleep-related characteristics
Atrial fibrillation (including silent, undiagnosed atrial fibrillation) is the most common cardiac
arrhythmia. It is associated with a doubling of the death rate and with substantial increases
in severe cardiovascular complications such as stroke, acute coronary syndrome, and heart
failure.
Many clinically relevant ECG changes such as atrial fibrillation are transient, and the search
for such changes can be lengthy and cumbersome, e.g., evaluating syncope or palpitations.
Conventional Holter ECG recordings often miss transient ECG changes (e.g., intermittent
atrial fibrillation, paroxysmal tachycardias, or intermittent AV block). In the National Cohort,
we aim to record at least a 24-h holter ECG, if possible taking a 7-day recording. Simple,
easy-to-carry-and-apply automatic and/or patient-activated ECG recording systems make it
possible to record an ECG over an extended period of time (e.g., 7 days) in epidemiologic
studies.
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