Quick answers
- Which hospitals does John D. Granquist work at?
- Medicare's official clinician data lists John D. Granquist at 5 hospitals: Hartford Hospital, Manchester Memorial Hospital, Middlesex Hospital, Midstate Medical Center and William W Backus Hospital. This is where the clinician works or has privileges; call the hospital to confirm.
- Where does John D. Granquist see patients?
- Medicare's clinician data lists 6 practice locations, including Avon, CT, Wallingford, CT and Glastonbury, CT. Call before your visit to confirm the address.
- What is John D. Granquist's specialty?
- Medicare lists Cardiovascular Disease (Cardiology) as the primary specialty.
- Does John D. Granquist accept Medicare assignment?
- Yes. Medicare's clinician data says John D. Granquist accepts Medicare assignment (the Medicare-approved amount as full payment for covered services), as of 2026-10-02. Ask the office to confirm before your visit.
- What is the phone number for John D. Granquist?
- (860) 522-0604, as listed in official Medicare / NPI Registry data.
- What is John D. Granquist's NPI number?
- 1699821892. The NPI (National Provider Identifier) is the clinician's permanent federal ID; you can look it up in the official NPI Registry.
Hospitals where John D. Granquist works
Medicare's Facility Affiliation Data lists John D. Granquist at these hospitals (updated 2026-10-02). Each hospital page shows its address, phone, emergency services, Medicare rating and all its clinicians.
- Hartford HospitalHartford, CT · Acute Care Hospital · CCN 070025
- Manchester Memorial HospitalManchester, CT · Acute Care Hospital · CCN 070027
- Middlesex HospitalMiddletown, CT · Acute Care Hospital · CCN 070020
- Midstate Medical CenterMeriden, CT · Acute Care Hospital · CCN 070017
- William W Backus HospitalNorwich, CT · Acute Care Hospital · CCN 070024
Practice locations
Addresses where John D. Granquist is enrolled with Medicare (CMS data updated 2026-10-02). The first 5 of 6; the Medicare profile lists all.
- 100 Simsbury Rd, Suite 202Avon, CT 06001 (860) 522‑0604
- 1062 Barnes Rd, Suite 300Wallingford, CT 06492 (203) 265‑9831
- 305 Western Blvd, Suite 100Glastonbury, CT 06033 (860) 522‑0604
- 435 Lewis AveMeriden, CT 06451 (203) 694‑8200
- 80 Seymour StHartford, CT 06102
Group practices
Medicare enrollment lists John D. Granquist as a member of these groups (CMS data updated 2026-10-02).
- Hartford Hospital1,044 clinicians in the group
- Midstate Medical Center186 clinicians in the group
- Consulting Cardiologists PC23 clinicians in the group
Specialties
Find other Cardiovascular Disease (Cardiology) doctors in Connecticut →
Other cardiologists in Avon
Clinicians with the same Medicare primary specialty in Avon, CT — not a recommendation.
Clinician information
| Credential | MD |
|---|---|
| Medical school | Tufts University School Of Medicine |
| Graduation year | 2000 |
| Gender (as listed) | Male |
| Medicare assignment | Accepts (Medicare-approved amount as full payment) |
| NPI (National Provider Identifier) | 1699821892 |
| 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 2026-10-02, retrieved 2026-10-29
- National Downloadable File (Doctors and Clinicians) — CMS, data updated 2026-10-02, retrieved 2026-10-29
- 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