**3.8 Sudden cardiac death in HCM**

Yearly mortality rate in subjects with HCM is in the order of 2 to 4% of the HCM cases; this is largely based on patients cared for in large tertiary care centers.

#### **Figure 6.**

*Apical five-chamber view with continuous-wave doppler across the left ventricular outflow tract demonstrating a peak gradient of 75 mmHg. The triangular pattern of the doppler recording is suggestive of subaortic narrowing.*

#### **Figure 7.**

*Parasternal long-axis views of the left ventricle of a patient with hypertrophic cardiomyopathy showing marked inter-ventricular septal thickening (arrows). LA, left atrium.*

Consequently, the true population prevalence is unknown. Examination of SCD in competitive athletes revealed that HCM is the most frequent reason for SCD and accounted for 36% of deaths [5–7]. The mortality is largely confined to the 12-to-35-year age patient group. Most of these patients are asymptomatic or mildly

*Pre-Sports Participation Cardiac Screening Evaluation – A Review DOI: http://dx.doi.org/10.5772/intechopen.102942*

#### **Figure 8.**

*Subcostal view of the left ventricle (LV) of a patient with hypertrophic cardiomyopathy showing marked inter-ventricular septal thickening (arrows).*

symptomatic and therefore, risk stratification of HCM is difficult. In some investigations, risk factors for SCD in HCM patients have been identified and these include, a family history of sudden death related to HCM, history of syncope or pre-syncope, history of having survived sudden death episode, massive LV hypertrophy (> 30 mm), non-sustained ventricular tachycardia, unusual blood pressure (BP) response to exercise, and high LV outflow tract gradient [1–4, 11–13].

#### **3.9 Sudden cardiac death prevention in HCM**

The mechanism by which HCM results in SCD following exercise is not clearly understood, but the development of ventricular arrhythmia, leading to ventricular fibrillation is thought to be responsible for SCD [2]. Even at the present time, we have limited knowledge as to how to prevent SCD in HCM. We continue to lack sound criteria of individual severity and relative prognostic risk, in general, and especially in athletes. Early studies showed the usefulness of beta-blockers in reducing mortality, but recent studies did not corroborate the usefulness of beta-blocker usage in the prevention of mortality. Exercise limitation may be helpful in decreasing the probability of sudden death. Indeed, the athlete with HCM should not be permitted to take part in the strenuous sports activity. If non-sustained ventricular tachycardia is present, Amiodarone has been shown to be beneficial. Intra-cardiac defibrillators (ICDs) for high-risk patients with ventricular tachycardia induced by programmed ventricular stimulation may be helpful.

#### **Figure 9.**

*Apical four-chamber view of the left ventricle (LV) of a patient with hypertrophic cardiomyopathy showing marked inter-ventricular septal thickening (arrows). RA, right atrium.*


#### **Table 1.**

*Criteria to distinguish athlete's heart from HCM.*
