Hypertrophic Cardiomyopathies

Hypertrophic Cardiomyopathies

Hypertrophic cardiomyopathy is an inherited cardiovascular disease [1]. The condition can lead to sudden death in young adults and other problems such as heart failure, arrhythmias and stroke. It is prevalent in the world, with cases reported in over 50 countries and in people of all sexes, ethnicities and races. In diverse regions including the USA, Europe and East Africa, the prevalence of hypertrophic cardiomyopathy is 1 in 500 in the general population [2]. While considered a common and possibly fatal disease, most affected individuals remain undiagnosed in their lifetime and do not experience symptoms or reduced life expectancy [1].

Hypertrophic cardiomyopathy is passed on by an autosomal dominant fashion through mutations in more than 12 genes that encode for thick and thin myofilament proteins. However, sporadic cases caused by de-novo mutations in the predisposing genes can also occur [3]. Genetic testing for the identification of causative mutations can be conducted via DNA sequencing; however, pathogenic mutations are identified in roughly fewer than 50% of clinically affected patients [1].

Clinical Presentation, Signs and Symptoms

Clinical diagnosis of hypertrophic cardiomyopathy entails a hypertrophied but non-dilated left ventricle without evidence of any other disorders, such as cardiac or systemic diseases that may cause cardiomyocyte hypertrophy [4]. Often, patients with hypertrophic cardiomyopathy do not have any symptoms, and diagnosis is made either incidentally or through familial genetic screening. However, symptomatic patients may experience chest pain with exertion and varying rates of dyspnoea on a daily basis. Chest pain may also present at rest and can be caused by large meals. Some patients can also experience syncope [5]. Dyspnoea, chest pain and syncope are common symptoms that we faced in the emergency department. Although there are more common and deadly presentations with those symptoms, hypertrophic cardiomyopathy should always be in our differential diagnoses, particularly in cases with additional findings explained below.

Clinical Exam and Investigations

Clinical examination of patients with hypertrophic cardiomyopathy often reveals little information. In patients with dynamic left ventricular outflow tract obstruction, a systolic murmur may be heard with auscultation at the left sternal edge, radiating to the aortic and mitral areas [5]. However, if hypertrophic cardiomyopathy is suspected, either due to familial screening, the presence of a murmur or an abnormal 12-lead electrocardiogram (ECG), its diagnosis needs to be confirmed with either echocardiography and/or cardiovascular MRI [1].

Natural History and Clinical Course of Hypertrophic Cardiomyopathy

Hypertrophic cardiomyopathies can present at any age from infancy to adulthood. Many patients with this cardiovascular disease are expected to have a normal life expectancy without any major complications or even therapeutic interventions [6]. However, complications may occur in some patients and can include a range of events. Sudden death may occur in patients who are mildly symptomatic or even asymptomatic. Progressive heart failure with possible obstructive outflow obstruction and normal systolic function can occur, which may slowly lead to systolic dysfunction [4]. Cardiac arrhythmias may also develop – most commonly atrial fibrillation. This can lead to symptoms of heart failure and embolic stroke in 20% of the patients [7].

Sudden Death

Sudden death is the most unpredictable and devastating consequence of hypertrophic cardiomyopathy and is the most common cause of sudden death in young patients (under the age of 30) and young athletes [1,4,8]. However, the risk of sudden death falls gradually with older age. Although sudden death from mild physical activity or even inactivity can occur, death due to vigorous exertion amongst this patient population is more common [1]. Sudden death from hypertrophic cardiomyopathy usually occurs due to ventricular fibrillation and tachycardia. Risk stratification of high-risk patients for sudden death is important and can lead to the prevention of sudden death using various approaches, such as an implantable defibrillator [1,9]. Additionally, young professional athletes should be screened to detect silent signs of cardiovascular disorders that may lead to sudden death. Unfortunately, if young athletes are found to have hypertrophic cardiomyopathy, implementation of a cardiovert-defibrillator is not sufficient to grant athletes to return to competing. Athletes are often advised to stop participating in competitive sports, unless it is of low intensity such as golf [8].

Heart Failure

Symptoms of heart failure associated with preserved left-ventricular systolic function most often occur in middle-aged patients but can occur at any age [13]. Functional limitations can occur at differing rates but are often gradual and involve day to day variability. Women with hypertrophic cardiomyopathy have been shown to experience more severe symptoms of heart failure later in life compared to male patients. Frequently, these symptoms experienced in women have been associated with left-ventricular outflow-tract obstruction [14]. Some causes of heart failure in hypertrophic cardiomyopathy patients include left-ventricular outflow-tract obstruction, atrial fibrillation and diastolic dysfunction [1,4]. Treatment strategies include drugs and surgical myectomy or alcohol septal ablation for relief of symptoms of heart failure and outflow obstruction, and pharmacological strategies to treat atrial fibrillation and prevent stroke (such as blood thinners).

Hypertrophic Cardiomyopathy Management in the ED

Patients with hypertrophic cardiomyopathy exacerbation may present to the ED with a range of symptoms including syncope, chest pain, dyspnea, cardiac arrhythmia and worst of all, sudden cardiac death [10]. Diagnosis of hypertrophic cardiomyopathy patients presenting with these symptoms to the ED may be difficult as most of these patients are not aware of their underlying cardiovascular disease. Therefore, ED staff should keep this differential in mind and should be aware of certain diagnostic tools and approaches for acute management of hypertrophic cardiomyopathy.

Primarily, ED staff should conduct a complete history of the patients, including family history of relatives with early cardiovascular disorders or sudden death at a young age. Physical examination of the patient may be inconclusive, as patients usually don’t present with any specific cardiovascular symptoms, unless their disease has progressed to having left-ventricular outflow obstruction tract. An electrocardiogram (EKG) should be conducted, as most patients with hypertrophic cardiomyopathy will have abnormal EKGs. Specifically, their EKGs will show signs of left ventricular hypertrophy through large amplitude QRS, and deep, narrow Q waves particularly in the lateral leads if the patient has septal hypertrophy [11]. Physical examination should be coupled with EKG to rule out other cardiac problems.

HCM-pattern-with-asymmetrical-septal-hypertrophy
Adopted from - Ed Burns. Hypertrophic Cardiomyopathy (HCM). https://litfl.com/hypertrophic-cardiomyopathy-hcm-ecg-library/

Deep narrow Q waves in chest leads are typical ECG finding of the hypertrophic cardiomyopathy patients. For more ECG information please visit – https://litfl.com/hypertrophic-cardiomyopathy-hcm-ecg-library/

In managing hypertrophic cardiomyopathy patients, following the ACLS algorithm if the patient is hemodynamically unstable is first priority. Otherwise, the goal of acute treatment of hypertrophic cardiomyopathy is to restore normal sinus rhythm or control the ventricular rate. Appropriate vasopressors should be given if patients are experiencing volume fluctuations due to diarrhea or other consequences of their disease. If patients present with a new onset of atrial fibrillation, approach of rate versus rhythm control and thromboembolism risk management should be considered [10]. If acute pharmacological treatment of hypertrophic cardiomyopathy patients is required, caution should be taken considering the state of their disease. For example, caution must be exercised when giving diuretics to patients with severe heart failure, as reduction in left ventricular preload can exacerbate obstruction and lead to hypotension [12]. The same considerations must be applied to any other treatment and guidelines should be followed closely. In conclusion, quick identification of the patient’s underlying cardiovascular problem and acute pharmacological management in the ED is critical to help the patient until a specialist can see them.

References and Further Reading

  1. Maron, B. J., & Maron, M. S. (2013). Hypertrophic cardiomyopathy. The Lancet381(9862), 242-255.
  2. Maron, B. J., Gardin, J. M., Flack, J. M., Gidding, S. S., Kurosaki, T. T., & Bild, D. E. (1995). Prevalence of hypertrophic cardiomyopathy in a general population of young adults: echocardiographic analysis of 4111 subjects in the CARDIA study. Circulation92(4), 785-789.
  3. Alcalai, R., Seidman, J. G., & Seidman, C. E. (2008). Genetic basis of hypertrophic cardiomyopathy: from bench to the clinics. Journal of cardiovascular electrophysiology19(1), 104-110.
  4. Maron, B. J. (2002). Hypertrophic cardiomyopathy: a systematic review. Jama287(10), 1308-1320.
  5. Elliott, P., & McKenna, W. J. (2004). Hypertrophic cardiomyopathy. The Lancet363(9424), 1881-1891.
  6. Maron, B. J., Casey, S. A., Hauser, R. G., & Aeppli, D. M. (2003). Clinical course of hypertrophiccardiomyopathy with survival to advanced age. Journal of the American College of Cardiology42(5), 882-888.
  7. Olivotto, I., Cecchi, F., Casey, S. A., Dolara, A., Traverse, J. H., & Maron, B. J. (2001). Impact of atrial fibrillation on the clinical course of hypertrophic cardiomyopathy. Circulation104(21), 2517-2524.
  8. Maron, B. J. (2003). Sudden death in young athletes.New England Journal of Medicine349(11), 1064-1075.
  9. Maron, B. J., Shen, W. K., Link, M. S., Epstein, A. E., Almquist, A. K., Daubert, J. P., … & Estes, N. M. (2000). Efficacy of implantable cardioverter–defibrillators for the prevention of sudden death in patients with hypertrophic cardiomyopathy.New England Journal of Medicine342(6), 365-373.
  10. Gardner, M., Nair, V., Hu, D., & Derry, S. (2018). The evaluation and management of decompensated hypertrophic cardiomyopathy in the emergency department.The American journal of emergency medicine36(12), 2286-2288.
  11. Kelly, B. S., Mattu, A., & Brady, W. J. (2007). Hypertrophic cardiomyopathy: electrocardiographic manifestations and other important considerations for the emergency physician.The American journal of emergency medicine25(1), 72-79.
  12. Efthimiadis, G. K., Pagourelias, E., Zegkos, T., Parcharidou, D., Panagiotidis, T., Arvanitaki, A., … & Karvounis, H. (2016). An overview of pharmacotherapy in hypertrophic cardiomyopathy: current speculations and clinical perspectives.Reviews in Cardiovascular Medicine17(3-4), 115-123.
  13. Melacini, P., Basso, C., Angelini, A., Calore, C., Bobbo, F., Tokajuk, B., … & Thiene, G. (2010). Clinicopathological profiles of progressive heart failure in hypertrophic cardiomyopathy.European heart journal31(17), 2111-2123.
  14. Olivotto, I., Maron, M. S., Adabag, A. S., Casey, S. A., Vargiu, D., Link, M. S., … & Maron, B. J. (2005). Gender-related differences in the clinical presentation and outcome of hypertrophic cardiomyopathy.Journal of the American College of Cardiology46(3), 480-487.

 

Cite this article as: Maryam Bagherzadeh, Canada, "Hypertrophic Cardiomyopathies," in International Emergency Medicine Education Project, December 9, 2020, https://iem-student.org/2020/12/09/hypertrophic-cardiomyopathies/, date accessed: October 17, 2021

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