Provider records sourced from NPPES (CMS National Plan & Provider Enumeration System). Data current as of October 4, 2026.
NPIDirectory

Koen Nieman, MD

Individual provider Specialist · NPI 1144778143

Koen Nieman, MD is registered under Cardiovascular Disease (Cardiology) in Stanford, California. Qualified in 1998, 28 years ago. Practices with Stanford Health Care, a 3,085-clinician group, accepts Medicare assignment and offers telehealth. Licensed in California and ZZ.

Years since qualifying
28
Licensed in
CA, ZZ
In the registry since
2016
Specialties on file
2
What do these letters mean?
MD — Doctor of Medicine
A physician who completed allopathic medical school.

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Practice location Address checks out

300 Pasteur Dr
Stanford, CA 94305-2200
Phone: (650) 723-4000
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Pin is approximate — placed at the ZIP-code centre, not the exact door.

Specialties & licences

Cardiovascular Disease Physician (primary) Taxonomy 207RC0000X · Licence A174597 (CA)
Specialist Taxonomy 174400000X · Licence 29048831401 (ZZ)

Record details

NPI number1144778143
Entity typeIndividual (Type 1)
GenderMale
Credentials MD
Sole proprietorNo
NPI enumeratedSeptember 19, 2016
Last updated in NPPESApril 24, 2024
Certification dateApril 24, 2024

Medicare enrollment

From the CMS Doctors & Clinicians file — this clinician is enrolled in Medicare.

Medicare specialtyCARDIOVASCULAR DISEASE (CARDIOLOGY)
Medical schoolOTHER
Graduated 1998 (28 years in practice)
Group practice Stanford Health Care — 3085 clinicians
Accepts Medicare assignment Yes — accepts the Medicare-approved amount
TelehealthOffers telehealth services
Practice locations5 on file with Medicare

Medicare patients and services, 2024

From the CMS Medicare Physician & Other Practitioners file for calendar year 2024. It counts Original Medicare patients only, so a practice that mostly sees Medicare Advantage or privately insured patients looks smaller here than it is.

Medicare patients1,988
Services billed 2,889 a service is one billed item, such as a visit, a test or a procedure
Average patient age75

Dollar amounts are not shown. What Medicare pays a practice is gross billings, before staff, premises and tax and including the cost of any drugs it administers, so it is not what a clinician earns.

Payments from drug and device companies, 2025

Drug and device makers are required by federal law (the Physician Payments Sunshine Act) to report what they pay or give to clinicians, and CMS publishes the reports as Open Payments. This is the 2025 program year. A report is a record of a payment, not an allegation of anything, and many are small items such as meals. Only general payments are listed here; research payments and ownership or investment interests are reported separately by CMS and are not shown.

Food and Beverage $291 4 payments · a meal or drink at a meeting or visit, not a fee
Travel and Lodging $47 1 payment · travel or lodging paid or reimbursed, such as to attend a conference

Each amount is the sum of what companies reported for that kind of payment in 2025, rounded to the dollar. Not all of it is income to the clinician: a meal is not a fee, a charitable contribution goes to a charity, and a royalty or an acquisition payment is not a salary.

Check a report, or dispute one, at the source in CMS’s own tool, Open Payments. Corrections go through CMS’s dispute process. This site removes a home address on request and asks for no proof, because that is privacy; it will not remove an accurate payment report on request, because that is a statutory public disclosure.

Practises at

Facilities the CMS Facility Affiliation file lists for this clinician. Those with a page here are linked.

Colleagues at Stanford Health Care

Clinicians the CMS Doctors & Clinicians file lists under the same group practice. CMS counts 3085 clinicians in the practice; 12 are shown here.

Other providers in Stanford