Anglo-Scandinavian Cardiac Outcomes Trial

Anglo-Scandinavian Cardiac Outcomes Trial
Name	Anglo-Scandinavian Cardiac Outcomes Trial
Other names	ASCOT
Acronym	ASCOT
Status	Completed
Location	United Kingdom, Sweden, Denmark, Norway, Finland, Ireland
Phase	III
Studied conditions	Hypertension, Coronary artery disease, Stroke
Interventions	Atenolol, Perindopril, Amlodipine, Atorvastatin, Hydrochlorothiazide, Angiotensin-converting enzyme inhibitor
Participants	~19,000
Start date	1994
Completion date	2005
Primary endpoints	Non-fatal myocardial infarction, Fatal coronary heart disease, Stroke

Anglo-Scandinavian Cardiac Outcomes Trial

The Anglo-Scandinavian Cardiac Outcomes Trial was a large randomized controlled trial comparing antihypertensive regimens and lipid-lowering therapy in adults at increased cardiovascular risk, enrolling participants across multiple United Kingdom and Scandinavia centers, and yielding influential evidence for management of hypertension and hyperlipidemia. The trial's dual randomization tested a calcium channel blocker–based strategy versus a beta-blocker–based strategy and included a nested statin trial, producing outcomes that informed guidelines from organizations such as the European Society of Cardiology and the National Institute for Health and Care Excellence.

Background

ASCOT was designed amid clinical debates between proponents of different antihypertensive classes, reflecting controversies involving investigators associated with institutions like St Bartholomew's Hospital, Karolinska Institutet, University of Oxford, University of Helsinki, and Trinity College Dublin. Contemporary trials and committees including members from World Health Organization, International Society of Hypertension, American Heart Association, British Hypertension Society, and European Society of Hypertension had variably endorsed beta-blocker or diuretic strategies influenced by landmark studies such as ALLHAT, LIFE, Syst-Eur, and meta-analyses by groups like the Cochrane Collaboration and researchers at Harvard Medical School and Johns Hopkins University. ASCOT sought to address unresolved questions raised after results from MRC trial of hypertension and debates involving investigators affiliated with GlaxoSmithKline, Pfizer, and academic centers including Imperial College London.

Methods

The trial randomized participants at risk for cardiovascular events from centers across United Kingdom, Republic of Ireland, Sweden, Denmark, Norway, and Finland to a calcium channel blocker–based regimen (primarily Amlodipine ± Perindopril) versus a beta-blocker–based regimen (primarily Atenolol ± Thiazide diuretic such as Hydrochlorothiazide). A nested lipid-lowering randomized component compared Atorvastatin to placebo in a subset with average or lower low-density lipoprotein cholesterol, overseen by trial committees with representation from European Medicines Agency and national regulators. Randomization, blinding procedures, and endpoint adjudication involved committees modeled after those at Duke University, Mayo Clinic, and trial statisticians trained in methods described by researchers at University College London. Primary endpoints included Non-fatal myocardial infarction and fatal Coronary heart disease, while secondary endpoints included Stroke, Heart failure, and all-cause mortality, adjudicated by panels using criteria similar to those in Framingham Heart Study protocols.

Results

ASCOT reported that the calcium channel blocker–based strategy reduced combined cardiovascular events and all-cause mortality compared with the beta-blocker–based strategy, with significant reductions in incidences of Non-fatal myocardial infarction and Fatal coronary heart disease, and lower rates of Stroke. The lipid-lowering arm demonstrated reductions in major coronary events with Atorvastatin versus placebo in individuals not selected for high low-density lipoprotein, consistent with findings from trials such as WOSCOPS and MIRACL. Results influenced clinician practice similar to uptake patterns following publications from Physicians' Health Study and Heart Protection Study, and were disseminated through journals and presentations at meetings like the European Society of Cardiology Congress and the American Heart Association Scientific Sessions.

Subgroup and Secondary Analyses

Pre-specified subgroup analyses examined heterogeneity by age strata akin to categorizations used in Framingham Heart Study analyses, by sex consistent with approaches from Women's Health Initiative, by baseline blood pressure levels comparable to HOT trial subgroups, and by regional differences among centers in Scotland, Wales, Northern Ireland, Stockholm, Oslo, and Copenhagen. Secondary analyses evaluated endpoints such as Peripheral arterial disease events, progression to Diabetes mellitus following definitions used in UKPDS, and quality-of-life measures using instruments validated at institutions like Karolinska Institutet and University of Oxford. Exploratory genomic and biomarker substudies involved collaborations with laboratories at Cambridge University and Karolinska Institutet and referenced methodologies from cohorts like ARIC and CARDIA.

Safety and Adverse Events

Safety monitoring identified class-specific adverse events including bradycardia and fatigue associated with Atenolol and edema associated with Amlodipine, with reporting standards informed by guidance from the European Medicines Agency and surveillance frameworks used by Food and Drug Administration. The trial documented incidences of new-onset Diabetes mellitus and adverse hepatic events in the lipid arm, with adjudication and pharmacovigilance procedures coordinated with national agencies such as the Medicines and Healthcare products Regulatory Agency and the Swedish Medical Products Agency.

Interpretation and Impact

Findings from ASCOT contributed to shifting recommendations toward broader use of calcium channel blocker and renin–angiotensin system–based regimens and supporting statin use in primary prevention, echoing policy changes advocated by bodies like the National Institute for Health and Care Excellence, European Society of Cardiology, and panels convened by World Health Organization. The trial influenced teaching at medical schools including University of Oxford Medical School and Karolinska Institutet, informed guideline panels at organizations such as the British Cardiac Society and European Atherosclerosis Society, and shaped discussions among trialists at conferences hosted by Royal College of Physicians and Royal College of General Practitioners.

Funding and Conflicts of Interest

ASCOT received funding and provision of study medications from pharmaceutical companies including Pfizer and AstraZeneca and involved investigators from academic centers such as St Bartholomew's Hospital, Institute of Cardiovascular Research units at University College London and Imperial College London. Oversight and data analysis were conducted by independent committees modeled on governance structures used by trials at Duke University and Mayo Clinic, with disclosures to journals and regulatory agencies including the European Medicines Agency and the Medicines and Healthcare products Regulatory Agency. Category:Cardiovascular clinical trials