Matthew Mayich hospitalized after collapsing during workout at Arizona State; OHL and St. Louis Blues offer support amid 'possible cardiac event'

Table of Contents

1. Key Highlights:
2. Introduction
3. The incident: what happened and how authorities responded
4. Who is Matthew Mayich: background and development as a prospect
5. What “possible cardiac event” can mean: medical explanations and initial diagnostics
6. Sudden cardiac arrest in athletes: scale, risk factors and notable cases
7. Emergency response and survival: CPR, AEDs and preparedness at training sites
8. Cardiac screening, prevention and the debate over ECGs
9. How teams, leagues and schools manage communication and privacy after medical emergencies
10. Return-to-play decisions: what clinicians evaluate and potential outcomes
11. Real-world examples of athletes who collapsed and their outcomes
12. Practical steps for athletes, families and programs after an incident
13. The broader conversation: balancing athlete opportunity and safety
14. What to watch next in the Mayich situation
15. FAQ

Key Highlights:

• Matthew Mayich, a 21-year-old St. Louis Blues prospect and former Ottawa 67’s defenceman, collapsed after an off-ice training session at Arizona State University and is hospitalized with a reported “possible cardiac event.”
• The Ontario Hockey League and the St. Louis Blues have issued statements of support; ASU confirmed a hockey player collapsed but cited privacy rules when asked to identify him.
• The incident raises questions about cardiac screening, emergency response and return-to-play protocols for young athletes; immediate CPR and access to an AED are critical factors in outcomes for on-field cardiac events.

Introduction

A routine summer workout left a promising young hockey player in hospital and a hockey community holding its breath. Matthew Mayich, a 21-year-old defenceman who spent four seasons with the Ottawa 67’s and was selected by the St. Louis Blues in the sixth round of the 2023 NHL draft, collapsed after an off-ice session at Arizona State University’s outdoor track. Local media reported the episode as a “possible cardiac event,” and teams and leagues moved rapidly to express support for the player and his family.

The circumstances are familiar and alarming: an otherwise fit athlete suddenly loses consciousness following exertion. For teammates, coaches and fans the immediate questions are practical—what happened, how did emergency staff respond, and what will recovery and return to play look like? For medical professionals, sports administrators and parents the episode revives a broader debate about cardiac screening, the limits of prevention, and how best to prepare when rare but catastrophic events occur.

This article pulls together what is known about the Mayich incident, traces his career to date, explains the range of medical possibilities behind a “possible cardiac event,” reviews emergency response and screening practices in sport, and outlines what athletes and teams should consider as they navigate recovery and future participation.

The incident: what happened and how authorities responded

Reports indicate Mayich collapsed after completing a workout at Arizona State University’s outdoor track. ASU initially confirmed that a hockey player had collapsed during an outdoor exercise but declined to identify the athlete, citing privacy rules. Local outlets later named Mayich after confirming details.

The exact timeline and medical details released publicly are limited. The Arizona Republic, which first reported Mayich’s identity, described the episode as a “possible cardiac event.” The Ontario Hockey League issued a public message expressing thoughts and support to Mayich, his parents and the family, and recalled the respect he had earned over four seasons in the OHL. The St. Louis Blues posted a message on X extending support and noting that Mayich was undergoing medical treatment in Arizona.

That pattern—limited clinical detail, league and team statements focused on support, and reliance on local reporting for specifics—reflects both medical privacy protections and a cautious approach by organizations while families and medical teams manage diagnostics and treatment.

Why privacy matters Health information for student-athletes and professional prospects is subject to strict privacy protections. In the United States, the Health Insurance Portability and Accountability Act (HIPAA) restricts what medical personnel may disclose without patient consent. Universities and teams typically coordinate public statements with families and medical providers. That explains why ASU confirmed a medical emergency but did not immediately name the athlete; confirming identity often depends on family consent or direct requests from local media.

Immediate response: what saves lives When an athlete collapses, minutes matter. Successful outcomes for sudden cardiac arrest depend on rapid on-site recognition, immediate chest compressions (CPR), early defibrillation with an automated external defibrillator (AED) if the rhythm is shockable, and swift transport to advanced medical care. Details about the presence and use of an AED or bystander CPR in Mayich’s case were not disclosed. The fact that he was transported to hospital and is undergoing treatment indicates he received urgent care.

Who is Matthew Mayich: background and development as a prospect

Matthew Mayich, from Stoney Creek, Ontario, built a reputation as a dependable two-way defenceman over several seasons in major junior hockey. He played four seasons with the Ottawa 67’s in the Ontario Hockey League, appearing in 256 games and finishing his OHL career with 21 goals and 99 points. After the OHL he spent the 2025–26 season with Clarkson University, taking the college route that many prospects choose to develop physically and academically while retaining NHL eligibility.

After being selected in the sixth round of the 2023 NHL draft by the St. Louis Blues, Mayich entered a development track that typically combines conditioning, skill work, and exposure in summer pro-development programs. His selection in the later rounds reflects the NHL reality that many prospects drafted after the early rounds require measured development—seasoned junior play, NCAA competition, and targeted training—to reach NHL readiness.

The path from junior to college to NHL organization Mayich’s journey—major junior hockey followed by NCAA play and ongoing development with an NHL organization—mirrors a common path for North American prospects. Junior leagues such as the OHL provide heavy game experience and physical maturation, while NCAA hockey offers an environment emphasizing strength and conditioning, education, and different tactical systems. NHL teams monitor prospects’ workloads closely during the offseason and may recommend training programs at partner facilities. That Mayich was training at ASU’s outdoor track aligns with a trend of prospects and collegiate players seeking warm-weather training environments during summer months.

Community reaction Following news of the collapse, teammates, former coaches and fans expressed concern and support across social platforms. The OHL commissioner referenced Mayich’s contributions and noted the league was keeping his family in its thoughts. The Blues likewise sent a message of solidarity. For young prospects and their communities, such incidents quickly move beyond a single player and become focal points for conversations about medical preparedness and player welfare.

What “possible cardiac event” can mean: medical explanations and initial diagnostics

When reports use the phrase “possible cardiac event,” they deliberately leave room for a range of diagnoses. That wording indicates clinicians are investigating whether a cardiac cause prompted the collapse, but it does not confirm a final diagnosis. The differential diagnosis after a collapse during or after exertion is broad.

Common cardiac causes to investigate

• Sudden cardiac arrest (SCA): The abrupt cessation of effective heart pumping, usually due to a life-threatening arrhythmia such as ventricular fibrillation or pulseless ventricular tachycardia. SCA is the most immediately dangerous cause and is the emergency clinicians first address.
• Arrhythmias without structural heart disease: Young athletes sometimes experience electrical disorders such as Wolff-Parkinson-White syndrome, long QT syndrome, Brugada syndrome, or other channelopathies that predispose to dangerous rhythms during exertion.
• Hypertrophic cardiomyopathy (HCM): A genetic condition characterized by abnormal thickening of the heart muscle. HCM has been identified as a cause of sudden cardiac death in athletes, though its prevalence is low.
• Myocarditis: Inflammation of the heart muscle, often from viral infections, can precipitate arrhythmias and heart failure. In the years after the COVID-19 pandemic, myocarditis has received more attention as a possible risk factor in athletes following viral infection or vaccination, though large-scale studies show myocarditis remains uncommon.
• Anomalous coronary arteries: Congenital variants where a coronary artery arises from an unusual location can compromise blood flow during exertion.
• Ischemic events are rare in young athletes but can occur with unrecognized coronary anomalies or early-onset atherosclerosis in those with significant risk factors.
• Exercise-associated collapse unrelated to primary cardiac pathology: Dehydration, heat illness, syncope from neurally mediated reflexes, or severe electrolyte disturbances can cause collapse but would not technically be classified as primary cardiac events.

Initial hospital evaluation A collapsed athlete typically receives a rapid series of tests on arrival at hospital:

• Electrocardiogram (ECG) to identify arrhythmias, conduction abnormalities, or ischemic patterns.
• Blood tests including cardiac biomarkers (troponin) to assess myocardial injury and basic metabolic panels to detect electrolyte disturbances.
• Echocardiogram to evaluate heart structure and function, including wall motion and chamber sizes.
• Cardiac MRI if myocarditis or subtle structural disease is suspected.
• Continuous telemetry and possible electrophysiology consultation if a primary arrhythmia is suspected.
• Coronary imaging such as CT angiography or invasive coronary angiography in select cases.

Clinicians aim to stabilize the patient, identify reversible causes, and determine acute treatment—whether that means medical therapy, catheter procedures, implantable devices, or simply observation.

Why the exact diagnosis often takes time Establishing an underlying cause can require days to weeks of testing. Some arrhythmic disorders present intermittently and may not appear on a resting ECG. Blood markers may lag, and imaging sensitivity varies based on timing. Physicians prioritize immediate stabilization and then sequencing of tests to avoid unnecessary interventions.

Sudden cardiac arrest in athletes: scale, risk factors and notable cases

Sudden cardiac arrest in athletes is rare but devastating. Public attention spikes with high-profile events because the victims are young, fit and visible figures.

How rare is it? Estimating the incidence of sudden cardiac arrest in athletes depends on the definition used (competitive vs. recreational athletes, level of competition, sex and age groups) and on how cases are identified. Broadly, studies suggest SCA among competitive athletes occurs at a rate measured in the single digits per 100,000 athlete-years. That low incidence makes mass screening a complex public-health tradeoff because any screening program must balance sensitivity and specificity, cost and the potential for false positives that can sideline athletes unnecessarily.

Risk factors and warning signs Some athletes carry recognized risk markers: known congenital heart disease, family history of sudden cardiac death under 50, personal history of syncope with exertion, exertional chest pain, unexplained breathlessness, or known arrhythmic symptoms. In many tragic cases of SCA, however, there was minimal or no prior warning.

High-profile international examples Several recent incidents shaped public awareness of on-field cardiac events and the life-saving potential of immediate response:

• Christian Eriksen suffered cardiac arrest during the UEFA European Championship in 2021. Rapid bystander CPR and defibrillation saved his life, and he later returned to professional soccer with an implanted cardioverter-defibrillator (ICD) and club contracts.
• Fabrice Muamba, the Bolton Wanderers midfielder who collapsed during an FA Cup match in 2012, survived after 78 minutes of CPR and advanced care. He retired from playing afterward but became an advocate for public CPR training and AED access.
• Damar Hamlin, a Buffalo Bills safety, suffered cardiac arrest during an NFL game in January 2023. Quick on-field medical response, including immediate CPR and resuscitation, allowed the player to survive; the incident catalyzed leaguewide reviews of emergency protocols and greater public awareness of cardiac arrest.

Hockey-specific incidents The hockey community has faced its share of sudden collapses and cardiac events. Rich Peverley, an NHL forward, collapsed during a 2014 game and was later diagnosed with a cardiac condition. His playing career ended after that incident. Those episodes influenced teams’ on-ice medical readiness and the development of standardized emergency plans that include AED placement and trained medical personnel.

Lessons from prior cases Three consistent lessons emerge from notable incidents:

1. Immediate bystander action saves lives. When peers, trainers or medical staff begin CPR and use an AED within minutes, survival and neurologic outcomes improve dramatically.
2. Public access to AEDs at sporting venues matters. Facilities with visible and maintained AEDs achieve faster defibrillation times.
3. Post-event care and return-to-play decisions are complex. Even when athletes survive an event, the path back to competitive sport involves detailed cardiology evaluations and sometimes lifelong device implantation or activity modification.

Emergency response and survival: CPR, AEDs and preparedness at training sites

Every training site and team facility must assume that a medical emergency could occur. For teams at every level, preparedness is the single most effective prevention of a fatal outcome when a collapse occurs.

The chain of survival Emergency medicine uses the “chain of survival” framework:

• Early recognition and activation of emergency services.
• Immediate bystander CPR to maintain blood flow to vital organs.
• Rapid defibrillation when the underlying rhythm is shockable.
• Advanced life support by emergency medical professionals.
• Post-resuscitation care at a hospital.

Each link is essential. When one link is missing, survival chances decline.

Role of AEDs Automated external defibrillators are designed for use by bystanders and trained lay rescuers. Modern AEDs analyze heart rhythms and advise a shock only when indicated. When used quickly—ideally within the first few minutes after collapse—an AED can convert ventricular fibrillation to a normal rhythm and save lives. For venues where athletes train at high intensity—fields, rinks, tracks—placing AEDs within three minutes’ access time is considered best practice.

Training coaches and teammates CPR training for coaches, athletic trainers and even teammates should be routine. Knowing how to recognize collapse, call emergency services and begin chest compressions immediately can bridge the minutes until professional responders arrive.

Policy implications after on-field cardiac events Many organizations have tightened their preparedness standards after high-profile incidents. Best practices include:

• A written emergency action plan for each facility and event.
• Clearly marked AED locations and routine maintenance logs.
• Regular, documented CPR/AED training for staff.
• Pre-season medical briefings and clear chains of command for emergencies.

While the details of response in Mayich’s case were not disclosed, the presence of immediate care at university athletic facilities typically includes access to athletic trainers, emergency plans and transport arrangements with local EMS.

Cardiac screening, prevention and the debate over ECGs

When a young athlete collapses, the inevitable question follows: could this have been prevented by better screening? The answer is complicated.

Types of screening Pre-participation evaluations commonly include:

• A medical history and physical exam: standardized questionnaires ask about prior fainting, chest pain, family history of sudden cardiac death, and other red flags.
• Baseline vitals and possibly resting ECGs.
• Additional testing as indicated by symptoms or history: echocardiography, exercise testing, ambulatory rhythm monitoring.

ECG screening: benefits and controversies An ECG can detect electrical abnormalities and some structural conditions that predispose to SCA. Proponents argue that ECGs identify conditions that a history and physical exam may miss. Critics cite false positives, the need for expert interpretation, cost, and the possibility of unnecessarily excluding athletes from competition. International cardiology societies differ in recommendations: some European guidelines lean toward systematic ECG screening for athletes, whereas North American organizations have traditionally placed more emphasis on targeted screening based on history and exam.

Practical considerations for teams For collegiate and professional organizations, baseline cardiac testing has become more common. NHL and NCAA teams have medical staffs and cardiology consultants to evaluate abnormal findings. For youth and amateur sports, universal ECG screening is rarely mandated because of logistics and resource constraints; instead, education and targeted screening for those with symptoms or family history remain the more common approach.

Impact of viral myocarditis and recent pandemics Episodes of myocarditis following viral illnesses, including COVID-19, prompted renewed attention on post-infection clearance to return to exercise. Many programs now recommend a period of rest and a medical clearance pathway after symptomatic infections. That said, myocarditis remains a relatively rare cause of athletic collapse.

Screening will not eliminate all cases Even with sophisticated screening, some conditions remain occult until they manifest unexpectedly. That reality underlines the importance of emergency preparedness and rapid response as part of comprehensive athlete safety planning.

How teams, leagues and schools manage communication and privacy after medical emergencies

Organizations must balance transparency with respect for privacy and the family’s wishes. The first public statements typically offer support while deferring to medical teams for clinical details.

Coordinating messages Teams and leagues generally coordinate statements through their communications department and receive input from medical staff and the athlete’s family. Statements often:

• Express concern and support for the athlete and family.
• Confirm that the athlete is receiving care.
• Commit to providing updates as permitted by the family and clinicians.

Why detailed medical updates are often limited Medical teams and families may restrict clinical details because:

• Privacy laws protect patient health information.
• Ongoing diagnostics may not yield immediate conclusions and can be misinterpreted.
• Families may want to control the pace of public disclosure during a stressful time.

Mental health and teammate care A collapse within a team can be traumatic for teammates, trainers and coaches. Organizations typically deploy counseling resources and psychological support to address acute stress reactions. Teams that prepare for this eventuality as part of their emergency plan can reduce secondary harm among teammates and staff.

Community and fundraising When young athletes face serious medical events, communities frequently mobilize support through social media messages, vigils and fundraising for medical expenses if needed. Professional organizations sometimes assist with logistics and counseling for families navigating hospital systems far from home.

Return-to-play decisions: what clinicians evaluate and potential outcomes

If a cardiac event proves to be a reversible or treatable condition, the question becomes whether and when the athlete can safely resume training and competition. Return-to-play (RTP) decisions after cardiac events are individualized and often conservative.

Typical RTP evaluation elements

• Clear identification and treatment of the underlying cause.
• Cardiology assessments including stress testing, ambulatory rhythm monitoring and imaging studies.
• Assessment of risk for recurrent arrhythmia or sudden cardiac arrest during exertion.
• Consideration of device therapy (e.g., implantable cardioverter-defibrillator) where indicated; an ICD has implications for return to contact sports.
• A graded reconditioning program with clinical supervision and reassessment.

Possible outcomes

• Full return to sport with clearance, when risk is low and reversible causes have resolved.
• Return with restrictions or monitoring, such as limiting high-intensity or collision sport activities.
• Permanent retirement from competitive sport when risk of recurrent life-threatening events is deemed unacceptably high.

Case-by-case nature Two athletes with similar clinical events can have completely different outcomes depending on precise diagnoses, response to treatment and patient priorities. The athlete’s age, level of competition and available medical resources also influence decisions.

Real-world examples of athletes who collapsed and their outcomes

No two cases are identical, but examining prior events helps illustrate how medical management and context shape outcomes.

Christian Eriksen During the UEFA European Championship, Christian Eriksen collapsed on the field due to cardiac arrest. Immediate CPR and defibrillation saved him. After hospitalization and further evaluation, Eriksen had an implanted cardioverter-defibrillator and later resumed professional play under cardiology supervision. His case highlighted the lifesaving impact of prompt on-site resuscitation and spurred broader calls for AED availability at sporting venues.

Fabrice Muamba Fabrice Muamba collapsed during an FA Cup match in 2012 and, after an extended resuscitation, survived but did not return to professional competition. He has since advocated for public awareness of CPR and AED access.

Rich Peverley An NHL veteran who collapsed during a game in 2014, Peverley’s incident ended his NHL career. His case drove conversations in hockey about in-arena medical readiness and cardiac screening practices for professional players.

Damar Hamlin A recent high-profile case in American football involved Damar Hamlin, whose on-field cardiac arrest in 2023 gained international attention. Rapid response by medical staff and subsequent hospitalization stabilized him. The incident prompted NFL-wide reviews of emergency medical protocols and renewed emphasis on CPR and AED training.

These examples show the spectrum of outcomes—from full return to play under monitoring to permanent retirement—and reinforce the central role of immediate care.

Practical steps for athletes, families and programs after an incident

When a training collapse occurs, there are practical and measurable actions athletes, families and programs can take to reduce risk and improve preparedness.

For athletes and families

• Take any episode of fainting, chest pain with exertion, palpitations or unexplained breathlessness seriously and seek timely medical evaluation.
• Provide a full family history to medical providers, noting any relatives who died suddenly or had cardiac conditions at a young age.
• If diagnosed with a cardiac condition, discuss the full range of management options and the implications for competitive sport and long-term health.

For teams and programs

• Maintain a documented emergency action plan for all training and competition sites.
• Keep AEDs in accessible locations and document regular maintenance checks.
• Require CPR and AED training for coaches, athletic trainers and staff working with athletes.
• Implement consistent pre-participation evaluations and follow-up pathways for any flagged concerns.
• Ensure clear communication channels with local emergency services and hospital facilities.

For facility operators

• Ensure outdoor training sites, like tracks or fields, have clear routes for EMS access and that communications devices are available for emergency calls.
• Consider environmental risks such as heat exposure and hydration protocols when scheduling intense workouts.

The broader conversation: balancing athlete opportunity and safety

Competitive sport depends on pushing human performance limits. At the same time, protecting athletes from rare but catastrophic events requires deliberate policy choices. Universal screening policies, mandated ECGs, or blanket restrictions on high-intensity training are all options that carry tradeoffs.

Evidence-driven policy Leagues, governing bodies and collegiate programs must ground decisions in evidence balancing risk reduction and the practicalities of implementation. That includes:

• Collecting reliable incidence data to understand the actual burden of cardiac events in defined athlete populations.
• Assessing the cost-effectiveness and psychological impacts of broader screening strategies.
• Ensuring emergency infrastructure is in place where athletes train and compete.

Supporting athletes holistically Medical safety does not end with prevention and emergency response. Mental health support and careful, transparent communication are essential when athletes face serious health threats. Programs that support athletes and families through hospitalization and rehabilitation reduce secondary harms and help preserve long-term well-being.

What to watch next in the Mayich situation

Expect a measured flow of information in the days and weeks following the incident:

• Clinical updates will likely come only with family consent. Initial statements from teams and leagues tend to emphasize support and privacy.
• If a definitive diagnosis emerges, medical teams may outline treatment and recovery plans. That information will determine potential return-to-play timelines.
• The hockey community will continue to rally and discuss whether any program-level changes are warranted in training-site preparedness.

For fans and concerned observers, patience is necessary. Immediate disclosure of detailed medical information is uncommon, both for privacy and because diagnostics often require time.

FAQ

Q: Has Matthew Mayich been identified officially by the university or team? A: Arizona State University confirmed that a hockey player collapsed during an outdoor workout but initially declined to name the athlete citing privacy. Local media outlets later reported the athlete as Matthew Mayich. The OHL and St. Louis Blues have issued statements of support but limited clinical details.

Q: What does “possible cardiac event” mean? A: The phrase indicates clinicians suspect the collapse may relate to a cardiac cause but have not issued a definitive diagnosis. It can include a range of conditions, from arrhythmias and myocarditis to structural anomalies like hypertrophic cardiomyopathy. Full diagnosis requires hospital-based testing.

Q: Could this have been prevented through screening? A: Some cardiac conditions can be detected through pre-participation screening that includes history, physical exam and, in some programs, ECGs or echocardiography. However, no screening program eliminates all risk because some conditions are intermittent or undetectable until a critical event occurs. That is why emergency preparedness and rapid response remain essential.

Q: What immediate actions save lives when an athlete collapses? A: Rapid recognition, immediate bystander CPR and quick defibrillation with an AED when indicated are the most important actions. Those interventions preserve blood flow and can restore a normal heart rhythm in shockable cases.

Q: Will Mayich be able to return to hockey? A: Return-to-play depends entirely on the final diagnosis, response to treatment and cardiology guidance. Some athletes return after reversible causes are addressed; others may have restrictions or be advised against returning. Decisions are individualized and made with medical input.

Q: What should teams and training sites do now to reduce risk? A: Ensure a written emergency action plan is in place, maintain accessible and functioning AEDs, train staff in CPR and AED use, confirm EMS access routes at outdoor sites, and implement appropriate pre-participation evaluations for athletes.

Q: Are AEDs commonly available at university training sites? A: Many universities and organized sports facilities maintain AEDs and have emergency protocols. Availability varies by institution. An incident like this typically prompts reviews of AED placement, maintenance and staff training.

Q: How common are sudden cardiac events in young athletes? A: Sudden cardiac events in competitive athletes are uncommon, occurring at a rate of a few per 100,000 athlete-years in many studies. Although rare, the high visibility and tragic consequences when they happen drive ongoing efforts to improve prevention and emergency response.

Q: What resources are available for teammates and staff affected by an incident? A: Athletic departments and professional teams usually provide counseling and psychological support services for teammates, staff and others affected. Programs with established mental health resources can deploy them quickly after a traumatic event.

Q: Where will updates about Mayich’s condition come from? A: Updates will most likely come through official channels—statements from the Blues organization, the OHL, Arizona State University (with family consent), or the athlete’s family. Respecting medical privacy, these updates may be limited while diagnostics and family decisions are ongoing.

The hockey community is watching as clinicians determine what led a young prospect to collapse during a training session. For now, messages of support from the OHL and the St. Louis Blues emphasize a focus on his well-being and the family’s privacy. The episode reinforces familiar public-health imperatives: routine cardiac screening can help in some cases, but it does not remove all risk; preparedness on-site and immediate, competent emergency response remain the most reliable defenses when rare events occur. As more information becomes available, medical findings will shape Mayich’s recovery plan and any subsequent conversation about prevention and safety for athletes at all levels.