Circulation Formatting Requirements: Complete Author Guide

Circulation requires a structured abstract for Original Research Articles. State-of-the-Art Reviews take an unstructured abstract of up to 350 words. The structure follows the standard clinical research format.

• Word limit: 300 words maximum on the article-types page (the manuscript-preparation page says 350 words, so the AHA's two pages differ; plan for 300)

• Structure: Background, Methods, Results, Conclusions

• Clinical trial registration: If the paper reports a clinical trial, the registry URL and unique identifier must appear at the end of the abstract, under the phrase "Clinical Trial Registration Information"

• Citations: Not permitted in the abstract

• Abbreviations: Define abbreviations at first use within the abstract, even if they're defined again in the main text

The Results section of your abstract should include actual numbers, not just qualitative statements. Write "The intervention reduced LDL-C by 38% (95% CI: 32-44%, P<0.001)" instead of "The intervention significantly reduced LDL-C." Circulation reviewers are quantitative, and vague abstracts signal weak data.

For Research Letters, no abstract is required.

A practical tip: keep the Background section to one or two sentences. Don't waste abstract space on general epidemiology. "Coronary artery disease remains the leading cause of death worldwide" is filler that every reviewer has read thousands of times.

Circulation sets a combined limit of 6 figures and tables for Original Research Articles. Planning your display items early matters because running out of slots mid-revision is a common problem.

Figure specifications:

Supplemental Material: Additional figures, tables, videos, and datasets can be uploaded as online Supplemental Material, which is included in peer review and must be submitted with the original manuscript. The AHA publishes no limit on the number of supplemental items. List them in the manuscript text, following the Acknowledgments, Sources of Funding, & Disclosures section (for example, Table S1, Figure S1, Video S1).

Tables in Circulation must be submitted as editable text, not as images. Each table needs a brief, informative title and a footnote defining any abbreviations used. Use horizontal rules only at the top, below the header row, and at the bottom. Vertical rules are not permitted.

Circulation uses the AHA Journals reference style, a numbered endnote style.

In-text citations: Numbers are assigned in order of first mention in the text, including figure and table legends, followed by references that are cited in the Supplemental Material only.

Reference list format:

1. Smith VA, Zhang J, Jones K. Article Title. Journal Name. 2015;100:555-559.

Key formatting details:

• Author names: Last name followed by initials, no periods between initials (e.g., "Smith JA")

• List the first 10 author names, followed by "et al."

• Volume and page numbers separated by a colon

• Year follows the journal abbreviation with a period and semicolon

Circulation's reference cap is 50 for Original Research Articles and 50 for State-of-the-Art Reviews. Don't pad your reference list with tangential citations just to show breadth. Reviewers notice, and it signals insecurity about the work.

Circulation's supplemental material lives online only and is permitted only for Original Research Articles and State-of-the-Art submissions.

What goes in the Supplemental Material:

• Additional figures and tables that support but don't drive the main narrative

• Detailed methods descriptions that exceed main text space

• Videos, audio files, and large datasets

• STROBE, CONSORT, or PRISMA checklists, when the journal asks for them (the AHA asks authors to be ready to provide the completed checklist, with line numbers, if requested during submission)

Formatting rules:

• List the supplemental materials in the manuscript text, following the Acknowledgments, Sources of Funding, & Disclosures section

• Label items as in the AHA's example list (Table S1, Figure S1, Video S1)

• Provide titles and legends for all supplementary display items

• Videos: Circulation's manuscript-preparation page lists avi, mov, and mpg files at a maximum of 10 MB, with larger files zipped, while the AHA's general guidelines recommend MP4 or MOV files, so the AHA's pages differ; check the live guide before uploading

• All supplementary material undergoes peer review

A practical tip: Circulation reviewers regularly request that authors move main-text figures into the supplement (or vice versa). Build your manuscript with this flexibility in mind. If Figure 3 is a supporting experiment rather than a core result, it's safer in the supplement from the start.

The Supplemental Material is also where you can include the full, unedited statistical output for clinical trials. The AHA Journals ask authors to follow their Transparency and Openness Promotion (TOP) guidelines, and having raw statistical tables in the supplement strengthens your position during review.

Circulation expects a title page as the first page of the manuscript file, and revised or accepted manuscripts must follow the journal's title page requirements.

Required cover page elements:

• Full title (the AHA publishes no title length limit)

• Short title (not to exceed 50 characters, including spaces)

• Authors' names, academic degrees, and affiliations

• Name, email address, and complete address of the corresponding author

• The total word count of the manuscript (including title page, abstract, text, references, tables, and figure legends)

Conflict-of-interest disclosure: The manuscript's Disclosures section must state all actual or potential perceived conflicts of interest, and authors with nothing to disclose must state "None". During revision, every author also completes a conflict-of-interest disclosure through Convey, a service run by the Association of American Medical Colleges that AHA Journals use for disclosures; each author receives a manuscript-specific link, and completion of all forms by all authors is required for revision submission.

For manuscripts targeting Circulation, three patterns generate the most consistent desk-rejection outcomes.

Clinical Perspective missing or generic. Circulation's author instructions ask authors to include a Clinical Perspective in Original Research manuscripts: "What is new?" (maximum 100 words, 2-3 bullets) and "What are the clinical implications?" (maximum 100 words, 2-3 bullets), placed after the abstract. A missing or generic Clinical Perspective weakens the first read. The bullets are not summaries of the abstract; they must state what is specifically new and what a cardiologist should do differently based on this study.

AHA conflict-of-interest disclosure not completed for every author. Every author must complete a conflict-of-interest disclosure during revision, through the Convey link the system provides for the manuscript, and completion of all forms by all authors is required for revision submission. In our review work, the most common failure is a revision where one or more co-authors have not yet completed their individual disclosure.

Surrogate endpoint primary outcomes where hard outcomes were feasible. Circulation editors scrutinize whether the chosen primary endpoint is appropriate for the patient population and study duration. A multi-year RCT in high-risk cardiovascular patients where the primary outcome is an imaging biomarker rather than MACE will receive editorial pushback.

A Circulation submission readiness check evaluates your Clinical Perspective, AHA disclosures, and endpoint appropriateness against these patterns.