Sudden death in hypertrophic and dilated cardiomyopathy
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1Third Department of Medicine, Kurume University School of Medicine, Japan.
Insights
Sudden death risk in hypertrophic cardiomyopathy (HCM) is higher in young patients with poor heart function. Dilated cardiomyopathy (DCM) patients may benefit from improved ventricular function to prevent sudden death.
Area of Science:
- Cardiology
- Clinical Medicine
- Electrophysiology
Background:
- Hypertrophic cardiomyopathy (HCM) and dilated cardiomyopathy (DCM) are significant causes of cardiac morbidity.
- Sudden death (SD) is a critical concern in patients with these cardiomyopathies.
- Identifying predictors of SD is crucial for risk stratification and management.
Purpose of the Study:
- To investigate clinical variables predicting sudden death (SD) in patients with hypertrophic cardiomyopathy (HCM) and dilated cardiomyopathy (DCM).
- To differentiate risk factors and mechanisms for SD based on age in HCM patients.
- To evaluate potential strategies for preventing SD in both HCM and DCM.
Main Methods:
- Long-term prognosis of 314 HCM patients and 82 DCM patients was analyzed.
- Clinical variables, including age, left ventricular function, and electrocardiographic findings, were assessed.
- Correlation between these variables and occurrence of sudden death was examined.
Main Results:
- In HCM, 68% of cardiac deaths were sudden. Young age (<30 years), reduced fractional shortening (<35%), and elevated left ventricular end-diastolic pressure (≥20 mmHg) predicted SD.
- In HCM patients <30 years, exercise-induced ischemia was a likely mechanism for SD. In those 30-50 years, ventricular tachycardia was more prevalent.
- In DCM, 24% of cardiac deaths were sudden; no reliable predictors were identified, but improved ventricular function may be key.
Conclusions:
- Young HCM patients with impaired systolic and diastolic function face a high risk of SD, necessitating exercise restriction.
- For HCM patients aged 30-50, controlling ventricular tachycardia with antiarrhythmic agents is advised.
- For DCM, improving ventricular function appears to be the primary strategy to prevent SD, as antiarrhythmic agents may cause hemodynamic compromise.
Abstract:
The long-term prognosis for 314 patients with hypertrophic cardiomyopathy (HCM) and 82 with dilated cardiomyopathy (DCM) was investigated in an attempt to elucidate clinical variables predicting sudden death (SD). In the patients with HCM, 68% of cardiac deaths occurred suddenly and unexpectedly. Variables associated with an increased risk to SD were young age (less than 30 years), reduced fractional shortening (less than 35%) and elevated left ventricular end-diastolic pressure (greater than or equal to 20 mmHg). Eight of the 10 patients who died suddenly during or immediately after strenuous exercise were less than 30 years old, and the collapse tended to be associated with exercise-induced ST-depression. In contrast, SD occurring during mild activities, resting or sleep was mainly observed in those aged 30 years or more. Ventricular tachycardia was observed on electrocardiographic monitoring in 24% of those 30 years or more, while it was rare in those under 30 years (5%). On the other hand, no SD was found in patients with apical hypertrophy nor in those 50 years or more. These observations suggest that HCM patients at a young age, with impaired left ventricular systolic and diastolic function, have an increased risk to SD. Since exercise-induced myocardial ischemia rather than ventricular arrhythmias appears to be the more likely mechanism for SD for those under 30 years old, restriction of strenuous exercise should be strongly advised for these patients. For those aged from 30 to 50 years, ventricular tachycardia should be controlled by antiarrhythmic agents for the prevention of SD. In patients with DCM, 24% of all cardiac deaths were attributed to SD. Although no variables reliably predicted SD, it was of note that only one patient out of 26 with SV1 + RV5 greater than or equal to 35 mm died suddenly. Whereas ventricular arrhythmias are known to be a contributing cause for SD, the prognostic significance of ventricular tachycardia on electrocardiographic monitoring in predicting SD has not yet been established. In addition, antiarrhythmic agents often precipitate hemodynamic deterioration. It therefore appears that use of antiarrhythmic agents is not a therapy of first choice and that primary treatment should be focused upon improvement in ventricular function in order to prevent SD in patients with DCM.