Quick answers
- Does Antonios Katsigiannis accept Medicare assignment?
- Yes. Medicare's clinician data says Antonios Katsigiannis accepts Medicare assignment (the Medicare-approved amount as full payment for covered services), as of October 2, 2026. Ask the office to confirm before your visit.
- How many Medicare patients does Antonios Katsigiannis see?
- In 2024, CMS data shows 89 Original Medicare patients and 369 services for Antonios Katsigiannis. This counts Original Medicare only and measures volume, not quality.
- What is Antonios Katsigiannis's NPI number?
- 1629157276. The NPI (National Provider Identifier) is the clinician's permanent federal ID; you can look it up in the official NPI Registry.
Medicare activity in 2024
Official CMS public-use data for Antonios Katsigiannis, data year 2024 (released May 21, 2026). It covers Original Medicare (fee-for-service) patients only, not Medicare Advantage or other insurance. It shows volume, not quality or outcomes. CMS hides any count of 10 or fewer patients.
| Original Medicare patients | 89 |
|---|---|
| Services billed to Medicare | 369 |
| Different services or procedures | 29 |
| Participating Medicare provider | Yes |
| Average age of these patients | 77 |
Most frequent services
- Established patient office or other outpatient visit with moderate level of decision making, if using time, 30 minutes or more (99214)179 services
- Established patient office or other outpatient visit with low level od decision making, if using time, 20 minutes or more (99213)33 services
- Routine electrocardiogram (ecg) using at least 12 leads with interpretation and report (93000)27 services
- Electrocardiogram (ecg) 1 to 3 leads with review by physician (93040)27 services
- Advance care planning, first 30 minutes (99497)16 services
Chronic conditions among these patients
Share of this clinician’s Original Medicare patients with each condition, as published by CMS (it describes the patients, not the care given).
- High blood pressure75%
- High cholesterol75%
- Arthritis44%
- Diabetes35%
- Anxiety29%
- Ischemic heart disease22%
Hospitals where Antonios Katsigiannis works
Medicare's Facility Affiliation Data lists Antonios Katsigiannis at these hospitals (updated October 2, 2026). Each hospital page shows its address, phone, emergency services, Medicare rating and all its clinicians. Star rating and emergency services: Hospital General Information (CMS), data updated October 26, 2026.
- Greenwich Hospital Association -Greenwich, CT · Acute Care Hospital · Medicare rating: 5 of 5 stars · Emergency services: listed by Medicare · CCN 070018
- St Vincent's Medical CenterBridgeport, CT · Acute Care Hospital · Medicare rating: 4 of 5 stars · Emergency services: listed by Medicare · CCN 070028
- Stamford HospitalStamford, CT · Acute Care Hospital · Medicare rating: 5 of 5 stars · Emergency services: listed by Medicare · CCN 070006
Practice locations
Addresses where Antonios Katsigiannis is enrolled with Medicare (CMS data updated October 2, 2026).
- 90 Morgan St, 101 102Stamford, CT 06905 (203) 323‑8437
Specialties
- Internal Medicineprimary
Other internal medicine doctors in Stamford
Clinicians with the same Medicare primary specialty in Stamford, CT — not a recommendation.
Clinician information
| Credential | MD |
|---|---|
| Medical school | New York Medical College |
| Graduation year | 1993 (33 years since medical school) |
| Gender (as listed) | Male |
| Medicare assignment | Accepts (Medicare-approved amount as full payment) |
| Telehealth | Offers telehealth services |
| NPI (National Provider Identifier) | 1629157276 |
| Corrections | Report an error or suggest an update → |
Most corrections must be made at the source: clinicians update their NPI Registry record (NPPES) and their Medicare enrollment (PECOS); this page follows the next data release.
Sources
- Facility Affiliation Data — Centers for Medicare & Medicaid Services (CMS), data updated October 2, 2026, retrieved October 29, 2026
- Hospital General Information — CMS, data updated October 26, 2026, retrieved November 13, 2026
- National Downloadable File (Doctors and Clinicians) — CMS, data updated October 2, 2026, retrieved October 29, 2026
- Medicare Physician & Other Practitioners - by Provider — CMS, data year 2024, released May 21, 2026; Medicare Physician & Other Practitioners - by Provider and Service
- NPI Registry — U.S. Department of Health and Human Services (NPPES), the clinician’s official record
- Medicare Care Compare — official Medicare tool to look up clinicians