Esperanza Perez was dining in a San Francisco restaurant when she felt dizzy, collapsed and went into sudden cardiac arrest. A nurse at a nearby table rushed to her side and began chest compressions.
Perez’s daughter did resuscitation while bystanders called 911. When Perez arrived at the hospital, the doctors learned she had gone through most of her life with a heart rhythm disorder. To prevent future cardiac arrests, they implanted a defibrillator.
Back in Miami, Perez went to see Dr. Robert Myerburg, who runs a clinic at UHealth for people who have had or are at risk for sudden cardiac arrest and sudden cardiac death. Myerburg questioned Perez extensively about her family heart history. After learning Perez’s grandmother and brother had sudden cardiac arrests, Myerburg recommended genetic testing.
The results showed Perez had a gene mutation. Additional testing on family members revealed that several carried the gene, too, including one of Perez’s children in her 30s, who has decided to implant a defibrillator to prevent cardiac arrest.
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“There is a lot you can do with genetic information,” Myerburg said. “If you just focus on that individual, it may not add anything. But when you test on other family members, the results become valuable.”
Many types of heart disease can be inherited, including some of the most common conditions and the rarer conditions. For common heart conditions such as high blood pressure or coronary artery disease, genetic testing is not yet available. But it is available and becoming more commonly used with conditions that affect the heart muscle called inherited cardiomyopathies.
Genetic testing, usually conducted through a blood sample, also is being used to learn more about inherited heart conditions that affect the electric system of the heart, causing abnormal heart rhythms called arrhythmias. The genetic testing identifies the mutation in the DNA responsible for the heart condition, although inheriting the mutation is not a guarantee that the disease will develop.
Unfortunately, unless identified in advance through genetic testing, the first time that certain heart diseases present themselves can be potentially fatal, such as the sudden cardiac arrests young athletes experience when they stop breathing on the sports field.
Dr. Myerburg said when a family member suffers sudden cardiac arrest, the rest of the family should undergo genetic testing. Then, family members who are diagnosed with an inherited heart condition can decide how aggressive to be with prevention.
He has patients who have learned of inherited heart conditions and are now being carefully watched or taking precautions. Options, he said, include starting medication, implanting a defibrillator or avoiding strenuous exercise.
“Most people will make the decision that’s comfortable for them,” he said.
South Florida cardiologists see a day when genetic testing could have broader uses.
Dr. Gervasio Lamas is the chairman of medicine and chief of the Columbia University Division of Cardiology at Mount Sinai Medical Center in Miami Beach. At his hospital, genetic testing still is used only to help a fraction of heart patients, he said.
There's no way to predict heart disease when complex genetic traits are just one of a family's many risk factors; environmental and lifestyle factors play a role, too, he said.
“Genetic testing for heart disease has not penetrated clinical practice for the most part and it’s mostly used in a way to explain something that already has occurred,” he said.
With most patients, even when there's a family tendency toward heart disease, the only thing to offer people is the same advice they already should be following for optimum heart health, he said. “It may be a future phase, but right now, we’re in the phase of the patient seeing the doctor and having the doctor guide treatment as best as possible.”
Yet, Lamas said genetic testing for heart disease results in drug development.
“Two new drugs came from observing and analyzing the genetics of high or low cholesterol,” he said. “It’s a different way of using genetics.”
In Kendall, Baptist Hospital conducted one of the largest studies of heart patients that included genetic testing. The hospital’s comprehensive heart study of more than 4,000 patients, known as the Miami Heart Study, looked at the connections between factors such as genetics and lifestyle to find out why heart attacks occur and attempt to lower the risks.
Dr. Lawrence Blacher, cardiologist at Miami Cardiac & Vascular Institute at Baptist Health South, said the genetic findings did little to help cardiologists manage the patients clinically.
“No one knows clearly what to do with the results,” he said. “They were complex. The patients didn’t understand them. The physicians didn’t either. Everything had a caveat and there was no way it could be applicable to the general population to predict who is going to have a heart attack.”
Instead, Blacher said, because the common heart conditions don’t have primary genetic influences, “the focus needs to be on better modalities for treatment, making people aware of their risk factors, getting them evaluated, getting them to lose weight and getting them to take medication.”
Meanwhile, at Cleveland Clinic Florida in Weston, cardiologist Craig Asher recognizes that for some heart conditions, genetics testing is only beginning to hold promise.
“Some of the testing we are doing is just building experience and learning. We are building databases and following patients and trying therapies and seeing if certain genes do better with certain treatments.
“Ultimately,” Asher said, “we want to be able to intervene with more types of heart conditions early, before they are clinically manifested, and intervene with different therapies — maybe even gene therapies.”