Radionuclide assessment of left ventricular function in hypertrophic cardiomyopathy

Area of Science:

• Cardiology
• Cardiac Electrophysiology
• Cardiovascular Imaging

Background:

• Hypertrophic cardiomyopathy (HCM) is a significant risk factor for sudden cardiac death.
• Left ventricular (LV) dysfunction is implicated in the pathophysiology of ventricular arrhythmias in HCM.
• Understanding the relationship between LV function and ventricular tachycardia (VT) is crucial for risk stratification.

Purpose of the Study:

• To investigate the association between left ventricular systolic and diastolic function and the occurrence of ventricular tachycardia in patients with hypertrophic cardiomyopathy.
• To identify specific echocardiographic parameters that may predict the risk of VT in HCM.

Main Methods:

• Eighty-four consecutive patients with HCM and sinus rhythm underwent 48-hour ECG monitoring.
• Technetium-99m gated equilibrium radionuclide angiography was performed to assess LV function.
• Key functional parameters including ejection fraction (EF), peak ejection rate (PER), peak filling rate (PFR), and time to peak filling rate (TPFR) were measured.

Main Results:

• Patients with VT (n=16) had significantly lower LV ejection fraction compared to those without VT (n=68) (67% +/- 17% vs. 78% +/- 10%, P < 0.05).
• Time to peak filling rate was significantly prolonged in patients with VT (152 +/- 32 ms vs. 120 +/- 36 ms, P < 0.05).
• These findings indicate impaired systolic and diastolic LV function in HCM patients with VT.

Conclusions:

• Patients with hypertrophic cardiomyopathy at the greatest risk of sudden death exhibit significant impairment in both systolic and diastolic left ventricular function.
• Radionuclide angiography can identify LV functional deficits associated with ventricular tachycardia in HCM.
• These functional parameters may aid in identifying HCM patients at higher risk for adverse cardiac events.