Kaiser Permanente Cardiac Malpractice Lawsuit, What Mathew Williamson’s $534 Million Case Alleges, Case No. UNVERIFIED

Mathew Williamson had a heart condition doctors were supposed to be watching closely. Instead, he says, he was put on a medication his own complaint calls dangerous for his exact diagnosis. On May 15, 2025, he went into cardiac arrest. He woke up to a body that had lost both legs above the knee. He’s now suing Kaiser Permanente and several treating physicians for negligence and recklessness, asking a jury to award close to $534 million.

Kaiser Permanente Cardiac Malpractice Lawsuit — Key Facts

Defendant	Kaiser Permanente and several treating physicians (individual physician defendants not confirmed by name in available reporting)
Plaintiff	Mathew Williamson, Portland, Oregon
Plaintiff’s Attorney	Mark Johnston, Portland, OR
Alleged Harm	Failure to properly diagnose and manage a worsening AV heart block, allegedly leading to cardiac arrest and bilateral above-knee leg amputations
Legal Claims	Negligence and recklessness (medical malpractice)
Who Is Affected	Plaintiff Mathew Williamson directly
Court & Case Number	UNVERIFIED — not named in available reporting; Portland-area malpractice suits of this size are typically filed in Multnomah County Circuit Court, but that has not been confirmed for this specific case
Lawsuit Filed	August 21, 2026
Current Stage	Newly filed; no hearing dates reported
Lead Plaintiff Deadline	Not applicable — this is an individual lawsuit, not a class action
Settlement Status	No settlement. No class. Single-plaintiff case
Last Updated	August 25, 2026

Who Is Kaiser Permanente and Why Are They Being Sued for Cardiac Malpractice?

Kaiser Permanente is one of the largest managed care organizations in the country, and its Permanente Medical Groups both insure and directly treat millions of patients across states including Oregon. That dual role — insurer and treating provider in one — is central to why this lawsuit names Kaiser and its physicians together rather than just one doctor. The complaint alleges the same organization responsible for Williamson’s ongoing cardiac monitoring is the one that allegedly missed how serious his condition had become. It’s not the first time Kaiser Permanente has faced a medical malpractice lawsuit over how it handled a patient’s care.

What Happened to Mathew Williamson Between His Diagnosis and May 15, 2025?

According to the complaint, Williamson had a documented history of AV block, a heart rhythm condition that disrupts the electrical signal between the heart’s upper and lower chambers. His case reportedly needed constant monitoring, and the block had been getting worse over time. He was started on metoprolol, a common heart medication — but his complaint alleges that drug “is not appropriate for those with serious AV block” without a pacemaker in place first.

The complaint says Kaiser and its providers were fully aware of Williamson’s diagnosis and test results in the months leading up to May 15, 2025. That day, he suffered a cardiac arrest severe enough to cause lasting damage throughout his body. The aftermath included above-knee amputation of both legs, fasciotomies on both arms that left him with serious loss of function, renal failure, a bowel injury requiring an ileostomy, and what the complaint describes as ongoing phantom limb pain. He’s still receiving treatment for complications tied to that day.

A heart medication that’s routine for most patients can be dangerous for the wrong diagnosis. That’s the entire allegation in one sentence, and it’s why the lawsuit treats this as a monitoring failure, not a random medical event.

What Kaiser Permanente Members With AV Block or Pacemaker Concerns Should Know

This isn’t a class action, so there’s no group to join and no shared payout if the case succeeds. But the underlying medical allegation — a heart-rhythm patient placed on a medication that the complaint says required a pacemaker first — is the kind of thing worth understanding even if you’re not involved in this specific case.

• Patients with a diagnosed or suspected AV block who are prescribed a beta blocker like metoprolol without a pacemaker discussion
• Anyone with worsening heart-block symptoms — dizziness, fainting, extreme fatigue — whose provider hasn’t recently reviewed their cardiac monitoring plan
• Patients managed across multiple Kaiser departments where test results and diagnoses may not have been clearly communicated between providers
• Family members currently navigating a loved one’s care after a sudden cardiac event tied to a pre-existing heart condition

If any of that sounds familiar, the right next step isn’t to self-diagnose a malpractice case from a news article — it’s to ask your own cardiologist directly whether your current medication is appropriate for your specific heart rhythm diagnosis.

Not sure whether a missed diagnosis or medication error in your own care rises to malpractice? A free consultation with a medical malpractice attorney can walk through the medical records with you before you decide whether there’s a case worth pursuing.

Kaiser Permanente Patients Outside Oregon — Does This Case Affect You?

This lawsuit is specific to Williamson’s treatment in Oregon and doesn’t extend to Kaiser members in other states. Kaiser operates as separate regional entities in California, Colorado, Georgia, Hawaii, Maryland, Virginia, Washington and Washington, D.C., and a malpractice claim against one region’s providers has no bearing on another region’s care. If you have separate concerns about Kaiser’s handling of patient data, that’s a distinct legal matter — Kaiser Permanente has settled other, unrelated class actions over how it handled patient information online.

What Is Mathew Williamson Asking the Court to Award?

The $534 million figure making headlines is really several separate numbers stacked together, and the complaint breaks them out individually rather than asking for one lump sum:

• Noneconomic damages: up to $500,000,000, with the exact amount left to a jury to decide
• Past medical expenses: approximately $2,716,202.90
• Estimated future medical expenses: $30,000,000
• Past lost income: $85,000
• Estimated impaired earning capacity: $1,000,000
• Plus 5% pre-judgment interest on the economic losses, plus court costs and disbursements

Add the components together and you land close to the reported $534 million — the noneconomic ceiling is doing almost all of the work in that total. No money has been awarded yet. This is a demand in a freshly filed complaint, not a verdict or a settlement.

What Could Williamson Actually Receive If This Case Succeeds?

Impossible to predict from the outside. Oregon juries set noneconomic damages within whatever cap state law allows for the claim type, and a $500 million ask is a ceiling the attorney is permitted to request, not a number courts typically award in full. What happens next depends on the medical evidence, how Kaiser responds, and whether the case settles before trial. A medical malpractice attorney familiar with Oregon damages caps can explain what verdicts in comparable catastrophic-injury cases have actually looked like.

What Should You Do If You Suspect a Missed Diagnosis Caused Serious Harm?

1. Request your complete medical records, including test results and every note from every provider involved in your care.
2. Write down the timeline yourself — when symptoms started, when tests were run, when treatment changed — while it’s still fresh.
3. Ask your current provider directly whether a prior diagnosis or medication choice was appropriate, and get that answer in writing if possible.
4. Save every bill, every missed paycheck, and every receipt tied to ongoing care — these become the economic damages figures in a claim.
5. Understand that most states, including Oregon, have a limited window to file a malpractice claim, so don’t sit on it.
6. Talk to a medical malpractice attorney before signing anything from an insurer or agreeing to any settlement offer.

Kaiser Permanente Cardiac Malpractice Lawsuit — Frequently Asked Questions

Is there a lawsuit against Kaiser Permanente over a missed heart diagnosis right now?

 Yes. Mathew Williamson filed suit against Kaiser Permanente and several treating physicians on August 21, 2026, alleging negligence in managing his AV heart block led to cardiac arrest and the amputation of both legs.

Do I need to do anything if I’m a Kaiser Permanente patient?

 No. This is an individual lawsuit, not a class action, so there’s no group to join and nothing to file related to this specific case.

Is this a class action against Kaiser?

 No. It’s a single-plaintiff medical malpractice case. Kaiser has separately settled unrelated class actions over patient data handling, but this cardiac case is not one of them.

How much money is Williamson seeking? 

Up to $500 million in noneconomic damages, plus roughly $2.7 million in past medical bills, $30 million in future medical costs, $85,000 in lost income, and $1 million in impaired earning capacity — a total close to the reported $534 million figure.

What does the lawsuit say went wrong medically?

 It alleges Williamson was prescribed metoprolol despite a worsening AV block, and that the complaint states that medication combination requires a pacemaker, which he didn’t have at the time of his cardiac arrest.

Has Kaiser Permanente responded to the allegations?

 Local reporting states Kaiser Permanente was contacted for comment; no public response had been reported as of this writing.

Will this case go to trial or settle? 

Too early to know. The complaint was filed August 21, 2026, and no hearing dates have been reported yet.

How can I follow updates on this case?

 Oregon circuit court filings are generally public record once indexed. Checking Multnomah County Circuit Court’s case search directly, or following Portland-area news coverage, is the most reliable way to track developments.

Sources Used in This Kaiser Permanente Cardiac Malpractice Lawsuit Article

• KATU (Portland, OR) — “Portland man sues Kaiser Permanente for $534M, alleging missed diagnosis led to amputations,” August 24, 2026: https://katu.com/news/local/portland-man-sues-kaiser-permanente-for-534m-alleging-missed-diagnosis-led-to-amputations-oregon-lawsuit-court-diagnosis-amputation-malpractice-tort-claims

Court docket and case number could not be independently verified through a public court index as of this writing. This article will be updated once the filing is located in a public record.

Researched and written by Israr Ahmad, legal content researcher and founder of AllAboutLawyer.com. All facts verified against KATU’s original reporting, as of August 25, 2026. Last Updated: August 25, 2026.

This article is for informational purposes only and does not constitute legal advice. Laws vary by state and individual circumstances differ. For advice about your specific situation, consult a qualified attorney or healthcare provider.