Blueprint Genetics

Cardiology case of the month: The path to a correct diagnosis

Mar 06, 2018

As genetic diagnostics is becoming a mainstream practice in the field of cardiology, new important information is found to form the basis for discovering the correct diagnosis and treatment of patients. Sometimes, genetic diagnosis can be extremely important in establishing the root cause of poor heart function.

Case: Catecholaminergic Polymorphic Ventricular Tachycardia (CPVT)

A teenager was successfully resuscitated from cardiac arrest. After the episode, the patient had severe heart failure and was diagnosed with a severe dilated cardiomyopathy (DCM) (LVEDD 60 mm and LV-EF<10 %) and atrial arrhythmias.

The patient also had a history of clinically confirmed paroxysmal atrial fibrillation and other atrial tachycardia. Within 24 hours of the cardiac arrest, she was treated with extracorporeal membrane oxygenation (ECMO), Milrinone, Levosimendan and catecholamines. During treatment the patient presented with increased short arrhythmia episodes.

The clinical question: was the poor heart function due to post-cardiac arrest?

Or was the primary myocardial disease DCM presenting with cardiac arrest? Were there some other reasons? The primary myocardial disease DCM was the strongest clinical suspicion.

A genetic test was made for 165 genes associated with cardiomyopathies (DCM, arrhythmogenic right ventricular cardiomyopathy (ARVC), and hypertrophic cardiomyopathy (HCM)), channelopathies and phenocopies (e.g. metabolic diseases).

Genetic diagnostics: the patient was identified with a heterozygous RYR2 missense variant

The result led to the diagnosis of catecholaminergic polymorphic ventricular tachycardia (CPVT). The attending clinician was contacted and informed about the potential risks of catecholamines, but the patient was deceased before establishment of the correct diagnosis.

Reaching the correct diagnosis to advance effective treatment 

Genetic testing as part of the clinical evaluation led to the primary diagnosis of CPVT instead of cardiomyopathy. The poor cardiac function was not likely caused by global damage during cardiac arrest, but instead by stunning (reversible) due to arrhythmias. The patient had been observed with arrhythmias in the past, likely of ventricular origin. As treatment the patient received catecholamines, which were likely harmful and increased her arrhythmias. The use of beta blockers and sympathectomy is effective treatment for CPVT. With timely diagnosis, the outcome may have had been better.

Hereditary cardiovascular diseases:

  • cardiomyopathies
  • channelopathies
  • aortopathies
  • connective tissue disorders
  • pulmonary arterial hypertension
  • congenital heart defects
  • rasopathies
  • inherited dyslipidemias

Learn more here.

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