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A Phase 2b/3 Randomized Double‑Blind Study of Ataciguat to Slow Disease Progression in Adults with Moderate Calcific Aortic Valve Stenosis

Fast replyInvestigationalNo placebo
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What is this trial about?

A plain-language summary of the goals, design and what participants do

People with Moderate Calcific Aortic Valve Stenosis have a heart valve that becomes thick and stiff, making it harder for blood to flow from the heart to the rest of the body. The study is testing an oral medication called Ataciguat, which is taken as a capsule each day, and comparing it with a placebo that looks the same but contains no active drug.

The purpose of the study is to find out whether the medication can slow the narrowing of the valve and improve the ability to exercise. Participants are randomly assigned to receive either the study drug or the placebo for about a year, with regular clinic visits. During the study, doctors will use an echocardiogram (an ultrasound picture of the heart) to see how big the valve opening is, and a peak VO2 test, measured during a CPET (a breathing and heart test done while exercising), to check how well the body uses oxygen. A CT scan (a detailed X‑ray picture) will also be performed to look at calcium buildup in the valve. If the valve becomes too narrow, doctors may discuss procedures such as TAVR (a catheter‑based valve replacement) or SAVR (surgical valve replacement).

Throughout the trial, participants will be monitored for any side effects, and safety checks will be done at each visit. The study team will collect information about health changes and any additional treatments needed, while keeping participants’ personal information confidential.

The research process

The trial runs in 6 steps – from screening to follow-up. Each step says what happens and what the team monitors.

  1. Step 1

    Baseline assessments

    After joining the study, you will attend a baseline visit. during this visit, an echocardiogram will be performed to measure the aortic valve area, a cardiopulmonary exercise test (cpet) will assess peak vo2, and a non‑contrast ct scan will evaluate the calcification score. these measurements establish the starting point for later comparisons.

  2. Step 2

    Randomization

    Based on the baseline results, you will be randomly assigned to receive either ataciguat or a matching placebo. the assignment is double‑blinded, meaning neither you nor the study staff will know which product you receive.

  3. Step 3

    Start of medication

    You will begin taking the study medication. the dose is one capsule containing 200 mg of ataciguat (or an identical placebo capsule) taken by mouth each day. the medication is taken for a total of 48 weeks.

  4. Step 4

    Daily dosing period

    Throughout the 48‑week period, you will continue the daily dose. you should keep a record of each dose and note any new symptoms or side effects. you will be asked to report these at scheduled study contacts.

  5. Step 5

    Week 48 final assessment

    At week 48, you will return for the final assessment. the same set of tests performed at baseline – an echocardiogram, a cpet to measure peak vo2, and a ct scan – will be repeated. the results will be used to determine the percent change in aortic valve area and the change in peak vo2.

  6. Step 6

    Study conclusion

    After the final assessment, the study medication will be stopped. the study team will discuss the overall results and any further clinical recommendations.

Who can join the trial?

5 criteria

  • Be at least 50 years old and be an adult, either male or female.
  • Have moderate calcific aortic valve stenosis (CAVS), which means the heart’s aortic valve is narrowed but not severely. This is shown by an aortic valve area (AVA) measured between 1.0 and 1.5 cm², and by a calcium score on a special scan (non‑contrast CT) that is between 600 and 1,200 Agatston units for women or between 600 and 2,000 Agatston units for men.
  • Have a left ventricular ejection fraction (EF) of 45% or higher when screened. This number tells how well the main pumping chamber of the heart is squeezing blood; 45% or more is considered adequate.
  • If you are taking a beta blocker medication, the dose must have stayed the same for at least 90 days before the screening visit, and you should not expect any changes during the study.
  • Meet any other requirements that are listed in the study protocol.

Who cannot join the trial?

9 criteria

  • Has had a previous aortic valve replacement (surgery to replace the valve that lets blood leave the heart), a repair, another type of surgery, or any other procedure on that valve, or plans to have one in the next 6 months.
  • Has moderate to severe problems with the mitral valve (the valve between the left upper and lower chambers of the heart) such as mitral stenosis (narrowing) or mitral regurgitation (leaking), or has moderate to severe leaking of the aortic valve (aortic regurgitation).
  • Has a known or suspected congenital aortic valve disease (a valve problem present from birth), including a bicuspid aortic valve (a valve with two leaflets instead of the normal three).
  • Has heart‑failure symptoms classified as New York Heart Association (NYHA) Class III or Class IV, meaning activity causes marked discomfort or the person cannot do any physical activity without feeling uncomfortable.
  • Has heart failure caused by something other than a problem with the aortic valve.
  • Has coronary artery disease (narrowing of the arteries that supply the heart) or is expected to need a coronary stent or heart‑bypass surgery.
  • Has an average QTcF interval of 480 milliseconds or longer on the screening heart test (ECG), or has risk factors for a dangerous rhythm called torsades de pointes, such as low potassium, a family history of long QT syndrome, or taking medicines that lengthen the QT interval, or has an abnormal ECG or ongoing atrial fibrillation (irregular fast heartbeat).
  • For participants in the exercise‑testing part of the study, has any medical or physical condition that, in the doctor's opinion, could prevent completing the required exercise test, such as lung disease, joint, leg, hip, or back problems that limit activity, or any other absolute reason not to do the test (CPET refers to the cardiopulmonary exercise test).
  • Any other reasons listed in the study protocol that would make participation unsuitable.
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Investigated drugs

Ataciguat is an oral capsule being studied as the active treatment in this trial. It belongs to a class of drugs that aim to improve the function of blood vessels and the heart. In the study, participants with moderate calcific aortic valve stenosis take Ataciguat to see if it can slow down the narrowing of the aortic valve (the opening through which blood leaves the heart). Researchers also want to know whether the medication can help improve the participants’ exercise capacity, measured by the highest amount of oxygen they can use during intense activity (peak VO₂). The trial is designed to compare the effects of Ataciguat with a placebo, but only the description of Ataciguat is shown here.

What is already known about the treatment

Ataciguat - Ataciguat is taken by mouth in a 200 mg capsule. It is still an experimental drug being studied in Phase 2b/3 trials for moderate calcific aortic valve stenosis and is not yet approved for general use. The medicine works by activating an enzyme called soluble guanylate cyclase, which raises levels of a molecule that helps blood vessels relax and may slow the damage to the heart valve. It is classified as a soluble guanylate cyclase stimulator.

Investigated diseases

Moderate Calcific Aortic Valve Stenosis - This condition involves a gradual buildup of calcium on the aortic valve, causing the opening to become narrower. As the valve area shrinks, less blood can leave the heart with each beat. The heart compensates by working harder to maintain blood flow. Over time the valve opening continues to decrease, which can limit the amount of oxygen-rich blood reaching the body. The narrowing typically progresses slowly, often over many years.
Trial detailsLast updated 2 Oct 2026
Age18+ yearsPhasePhase IIITrial ID2025-522176-86-01Protocol codeATA-301Estimated enrolment1 276 patientsSponsorKardigan Inc.

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On this site, “treatment” means an investigational medicine being studied in a clinical trial. Its safety and efficacy for the use being studied have not yet been confirmed, some participants may receive a placebo or a comparator medicine, and taking part does not guarantee any health benefit. The decision to take part is made by the doctor at the research site. This site is for information only and does not replace medical advice.

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