Quick answers
- Does Kenneth W. Mahaffey accept Medicare assignment?
- Yes. Medicare's clinician data says Kenneth W. Mahaffey 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 Kenneth W. Mahaffey see?
- In 2024, CMS data shows 845 Original Medicare patients and 966 services for Kenneth W. Mahaffey. This counts Original Medicare only and measures volume, not quality.
- What is Kenneth W. Mahaffey's NPI number?
- 1659455707. 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 Kenneth W. Mahaffey, 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 | 845 |
|---|---|
| Services billed to Medicare | 966 |
| Different services or procedures | 14 |
| Participating Medicare provider | Yes |
| Average age of these patients | 75 |
Most frequent services
- Routine electrocardiogram (ecg) using at least 12 leads with interpretation and report only (93010)767 services
- Heart rhythm review and interpretation of continous external ekg over 8-15 days (93248)67 services
- Established patient office or other outpatient visit with high level of medical decision making, if using time, 40 minutes or more (99215)29 services
- Routine electrocardiogram (ecg) using at least 12 leads with interpretation and report (93000)20 services
- Initial hospital care with straightforward or low level of medical decision making, per day, if using time, at least 40 minutes (99221)19 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%
- Ischemic heart disease47%
- Arthritis45%
- Atrial fibrillation45%
- Chronic kidney disease43%
Hospitals where Kenneth W. Mahaffey works
Medicare's Facility Affiliation Data lists Kenneth W. Mahaffey 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.
- El Camino HealthMountain View, CA · Acute Care Hospital · Medicare rating: 4 of 5 stars · Emergency services: listed by Medicare · CCN 050308
- Peninsula Medical CenterBurlingame, CA · Acute Care Hospital · Medicare rating: 5 of 5 stars · Emergency services: listed by Medicare · CCN 050007
- Santa Clara Valley Medical CenterSan Jose, CA · Acute Care Hospital · Medicare rating: 2 of 5 stars · Emergency services: listed by Medicare · CCN 050038
- Sequoia HospitalRedwood City, CA · Acute Care Hospital · Medicare rating: 5 of 5 stars · Emergency services: listed by Medicare · CCN 050197
- Stanford Health CareStanford, CA · Acute Care Hospital · Medicare rating: 5 of 5 stars · Emergency services: listed by Medicare · CCN 050441
Practice locations
Addresses where Kenneth W. Mahaffey is enrolled with Medicare (CMS data updated October 2, 2026).
- 2585 Samaritan DrSan Jose, CA 95124 (650) 723‑4000
- 300 Pasteur DrStanford, CA 94305 (650) 723‑4000
- 5565 W Las Positas Blvd, Suite 150Pleasanton, CA 94588 (650) 723‑4000
- 5800 Hollis StEmeryville, CA 94608 (510) 806‑2100
Group practices
Medicare enrollment lists Kenneth W. Mahaffey as a member of this group (CMS data updated October 2, 2026).
- Stanford Health Care3,122 clinicians in the group
Specialties
Find other Cardiovascular Disease (Cardiology) doctors in California →
Other cardiologists in San Jose
Clinicians with the same Medicare primary specialty in San Jose, CA — not a recommendation.
Other clinicians in Stanford Health Care
Medicare enrollment lists these clinicians in the same group practice — not a recommendation.
Clinician information
| Credential | MD |
|---|---|
| Medical school | University Of Washington School Of Medicine |
| Graduation year | 1989 (37 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) | 1659455707 |
| 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