A person can suffer a heart attack only three days after a knee replacement (or other joint replacement) surgery.

Just HOW does this happen?

You may already be aware that knee and hip replacement surgery greatly increases the risk of a heart attack – not long-term, but in the early postop period.

This can be pretty scary to someone about to undergo such an operation.

“To be clear, a knee replacement, in and of itself, does not cause a heart attack,” says Barbara Bergin, MD, board certified orthopedic surgeon at and co-founder of Texas Orthopedics, Sports & Rehabilitation Associates.

Why and how does a knee replacement surgery increase heart attack risk?

People over 60 are at greatest risk. Studies support this, such as one by Boston University School of Medicine that was published in Arthritis & Rheumatology, 2015.

Any stress to the body which results in a greater load to the heart can result in a heart attack or ischemia, especially in people with underlying cardiac disease,” says Dr. Bergin.

“Knee replacement can cause blood loss, which can increase the load placed on the heart.

“It is usually performed in older people, who are more likely to have underlying heart disease.” This may be either coronary artery disease, chronic heart failure or both.

Reason #1. Loss of hemodynamic balance. This means disruption of blood flow during surgery which can harm the heart.

Reason #2. Other underlying conditions which can make the patient more vulnerable to a heart attack include:

  • A body mass index greater than 30
  • Pre-existing heart rhythm disorder
  • Use of NSAIDS (non-steroidal anti-inflammatory medications such as ibuprofen)
  • Undergoing replacement on both knees simultaneously (Basilico et al, Arthritis & Rheumatology, 2008)

Reason #3. The patient’s body is not used to trauma.

In addition, “Immediately after surgery blood is a bit more hypercoaguable,” says Nieca Goldberg, MD, medical director of NYU Women’s Heart Program and radio show host of “Beyond the Heart” on Doctor Radio SiriusXM.

This means the blood is more prone to clotting — a blood clot can form in a coronary artery, resulting in a heart attack.

“Generally knee surgery is safe, and the majority of surgeries take place without heart attacks,” says Dr. Goldberg.

“For people who are at higher risk for heart attack, the orthopedist refers those individuals to a cardiologist to assess their risk before surgery.”

“Prehab” Will Lower the Risk of a Heart Attack Soon After Knee Replacement

First off, a BMI of at least 30 means obesity. So the higher one’s body mass index is, above 30, the greater the chance of a heart attack from any kind of surgery.

Prehab means taking measures prior to surgery to strengthen the body to lower the risk of postsurgical complications such as a heart attack.

The body is strengthened with exercise — which in turn can result in weight loss and a BMI under 30.

The longer that the knee replacement surgery is scheduled out for, the more time the patient has to make prehab work for him or her.

Exercise for Someone with Painful Knee Osteoarthritis

A person with bone-on-bone knee pain can do strength training workouts while seated upright, inclined back at an angle, or lying on a bench — sparing their knee joint from any pressure or pain.

A chronically sedentary person’s body is not used to the trauma of rigorous strength training. Their body is not used to recovering from trauma.

A hearty workout induces trauma to the body! Consistent exercise trains the body to recover more effectively from trauma.

If a physically fit person with knee osteoarthritis — whose body is used to intense chest, back and shoulder workouts —  undergoes a replacement surgery, their body may “think” that the operation is just another gym workout!

The load on their heart from the surgery may seem like just another challenging day at the gym.

On the other hand, if someone has a lifelong history of avoiding a challenging exercise regimen, a knee replacement surgery will be a tremendous shock to their system. And the heart does not like unexpected surprises.

Of course, a sedentary 70-year-old isn’t going to be able to whip his body into “Mr. Fitness” shape in only a few months.

However, even just eight weeks of a strength training program prior to the joint replacement will raise the chance of a favorable postop outcome.

Many older people with osteoarthritis are only in the consideration stages of knee replacement surgery.

They have even MORE time to prehab, and should not delay this a day longer.

Again, the workouts can be upper body only, and include the following exercises shown below.

Bench press. Shutterstock/Halfpoint


Cable biceps curls can be done while seated. Shutterstock/Lestertair


Overhead press. Shutterstock/CandyBox Images


Lat pull-down. Shutterstock/Monkey Business Images


Seated row. Freepik.com/yanalya.

Remember, a “shocked” body is more likely to suffer a heart attack from a knee replacement or ANY surgery.

Dr. Bergin is a general orthopedist, surgically and conservatively treating all manner of bone and joint conditions. She enjoys educating patients so they can emerge stronger than they were before their orthopedic injury or surgery.
Dr. Goldberg is senior advisor, Women’s Health Strategy, NYU Langone Health; founder and former medical director, Joan H. Tisch Center for Women’s Health; and clinical associate professor, NYU Grossman School of Medicine.
Lorra Garrick has been covering medical, fitness and cybersecurity topics for many years, having written thousands of articles for print magazines and websites, including as a ghostwriter. She’s also a former ACE-certified personal trainer.  
Top image: Shutterstock/ArtFamily