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Study Title and Description

Caffeine impairs myocardial blood flow response to physical exercise in patients with coronary artery disease as well as in age-matched controls.



Key Questions Addressed
1 For [population], is caffeine intake above [exposure dose], compared to intakes [exposure dose] or less, associated with adverse effects on cardiovascular outcomes?
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Primary Publication Information
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TitleData
Title Caffeine impairs myocardial blood flow response to physical exercise in patients with coronary artery disease as well as in age-matched controls.
Author M Namdar,T Schepis,P Koepfli,O Gaemperli,PT Siegrist,R Grathwohl,I Valenta,R Delaloye,M Klainguti,CA Wyss,TF Lüscher,PA Kaufmann,
Country
Year 2009
Numbers

Secondary Publication Information
There are currently no secondary publications defined for this study.


Extraction Form: Cardiovascular Design
Design Details
Question... Follow Up Answer Follow-up Answer
What outcome is being evaluated in this paper? Cardiovascular
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What is the objective of the study (as reported by the authors)? Our aim was to assess the acute effect of caffeine in a dose corresponding to two cups of coffee (200 mg) on myocardial blood flow (MBF) in coronary artery disease (CAD).
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Provide a general description of the methods as reported by the authors. Information should be extracted based on relevance to the SR (i.e., caffeine related methods) Study population: The age-matched control group consisted of 15 healthy volunteers (mean age 58613 years, 5 males, 10 females, P = ns vs. patients). Exclusion criteria were arrhythmia of any kind, a pathological ECG, existing cardiovascular risk factors, current medication affecting myocardial blood flow and/or cardiovascular risk factors and a more than low clinical probability for CAD. All participants were habitual coffee drinkers but refrained from ingesting caffeinated beverages or food for 24 hours before the study. Study protocol: With the subject’s feet attached to a bicycle ergometer (model 380 B, Siemens-Elema AG, Switzerland) MBF was measured at rest and during supine bicycle exercise-induced hyperemia in all study participants as recently documented [14,17]. Exercise was started at 25–50 Watts (W), and workload was increased every minute to reach 100% of the predicted value for upright bicycle exercise after 5 minutes. Thereafter, 200 mg of oral caffeine (GlaxoSmithKline, Pittsburgh, PA, USA) - a dose corresponding to two cups of coffee [3] – was administered to each subject and fifty minutes later (at the time of expected serum caffeine peak level) all MBF measurements were repeated. Blood pressure was continuously monitored by a Finapress Monitor (BOC; Inc., Englewood, CO, USA) and recorded every minute at rest, at each exercise level and during recovery. The ECG was monitored continuously and a 12-lead ECG was recorded each minute. Serum caffeine concentration was determined before and 50 minutes after caffeine ingestion.
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How many outcome-specific endpoints are evaluated? 4
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What is the (or one of the) endpoint(s) evaluated? (Each endpoint listed separately) Heart rate
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List additional health endpoints (separately). 2 Blood pressure
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List additional health endpoints (separately).3 Rate-pressure product
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List additional health endpoints (separately).4 Myocardial blood flow
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List additional health endpoints (separately).5
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List additional health endpoints (separately).6
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Clinical, physiological, other Physiological
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What is the study design? Controlled Trial
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Randomized or Non-Randomized? NCT
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What were the diagnostics or methods used to measure the outcome? Objective
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Optional: Name of Method or short description Blood pressure was continuously monitored by a Finapress Monitor (BOC; Inc., Englewood, CO, USA) and recorded every minute at rest, at each exercise level and during recovery. The ECG was monitored continuously and a 12-lead ECG was recorded each minute. Serum caffeine concentration was determined before and 50 minutes after caffeine ingestion.
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Caffeine (general) Caffeine (general)
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Coffee, Chocolate, energy drink, gum, medicine/supplement, soda, tea, other?
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Measured or self reported? Measured
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Children, adolescents, adults, or pregnant included? Adults
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What was the reference, comparison, or control group(s)? (e.g. high vs low consumption, number of cups, etc.) Information in this extraction is for the control group only (the exposed group was not a healthy population). The control group had baseline measurements.
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What were the listed confounders or modifying factors as stated by the authors? (e.g. multi-variable components of models.  Copy from methods) Exclusion criteria were arrhythmia of any kind, a pathological ECG, existing cardiovascular risk factors, current medication affecting myocardial blood flow and/or cardiovascular risk factors and a more than low clinical probability for CAD. Comparisons of hemodynamic and MBF values were performed by ANOVA statistics for repeated measures. When the P-value was <0.05, Sheffe’s procedure was applied. For paired comparison of stenotic versus remote segments and unpaired comparison of patients versus age-matched controls, a paired and an unpaired t-test were used, respectively. The number of patients necessary (in each group) was calculated to be fewer than 15, for detecting a minimum clinically relevant difference in hyperaemic MBF of 20% between baseline and caffeine with an alpha of 0.05 and a power (1-beta) of 0.8.
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What conflicts of interest were reported? Authors stated they had no competing interests.
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Refid 19479069
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What were the sources of funding? The corresponding author was supported by a grant from the Swiss National Science Foundation (SNSF-professorship grant No. PP00A-68835/1 and by the Jubilaeumsstiftung der Schweizerischen Lebensversicherungs- und Rentenanstalt fuer Volksgesundheit und medizinische Forschung Swiss Life).
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Results & Comparisons

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