Stress-induced Cardiomyopathy (SIC) is a temporary condition where a person’s heart muscle becomes suddenly weakened or ‘stunned’ and the left ventricle changes shape. Patients with SIC generally show no symptoms until they suffer some form of intense emotional or physiological distress. For this reason the disorder is sometimes referred to as broken heart syndrome, and because of its unusual presentation has captured the attention of physicians for centuries.
SIC, also known as or Takotsubo cardiomyopathy, is a poorly understood and under-diagnosed phenomenon. Now, a study from researchers at the Translational Genomics Research Institute (TGen) and Barrow Neurological Institute has for the first time identified genetic risk factors that are linked to SIC. The team state that knowing which patients harbor the genes associated with SIC could help guide their care and treatment before, and after, they suffer a life-threatening stressor that induces SIC.
Previous studies show that SIC or Takotsubo cardiomyopathy starts abruptly and unpredictably, with symptoms of chest pain and, often, shortness of breath, usually triggered by an emotionally or physically stressful event, and with a predilection for women older than 50 years of age. Most patients go to the emergency department because of concern they are experiencing a heart attack. In the early hours SIC and heart attacks share many similarities in presentation, including chest pain and breathlessness, as well as abnormalities in both the electrocardiogram and blood biochemical tests. It can therefore be challenged to distinguish between the two, until the salient diagnostics are performed. Therefore, the lab propose that SIC is an example of a hidden heart disease with a distinct physiological trigger, and suggest that alternative clinical approaches to these patients may be warranted. The current study identifies new genetic risk factors through the use of the powerful approach of genomic sequencing.
The current study followed 21 patients who were treated for hemorrhagic stroke between 2005-13, and who were diagnosed with SIC; none of the patients had significant prior cardiac history. The group used ultra-high resolution cameras and supercomputers to identify the suspect genes by next generation DNA sequencing, essentially by spelling out the billions of bits of information in the genomes of seven women who exhibited SIC following a brain aneurysm. Data findings identified a series of rare genetic changes associated with the disease that may be used for early identification of patients at risk.
Results show that the gene variants associated with SIC are MYLK2, DSG2, FKTN, and LDB3. The team note that all of these genes were previously known to play a role in cardiac diseases other than SIC and all of these variants are extremely rare. They go on to add that MYLK2 had previous been seen in only 1,539 individuals, DSG2 in 224 people, FKTN in just 3 people, and LDB3 had never before been sequenced.
The team surmise that identification of patients at risk for SIC, based on genetic predispositions, would allow for tailored treatment upon admission of these patients to the intensive care unit, and perhaps prior to a decline of the heart and brain. For the future, the researchers state that the panel of genes identified provides a means of identifying patients who may be at risk for developing this type of heart disorder, and may also be useful in helping to avoid SIC altogether.