Prognostic significance of radionuclide-assessed diastolic function in hypertrophic cardiomyopathy

To evaluate the prognostic significance of diastolic function in hypertrophic cardiomyopathy (HC), technetium-99m gated equilibrium radionuclide angiography, acquired in list mode, was performed in 161 patients. Five diastolic indexes were calculated. During 3.0 ± 1.9 years, 13 patients had disease-related deaths. With univariate analysis, these patients were younger (29 ± 20 vs 42 ± 16 years; p < 0.05), had a higher incidence of syncope (p < 0.025), dyspnea (p < 0.001), reduced peak filling rate (2.9 ± 0.9 vs 3.4 ± 1.0 end-diastolic volume/s; p = 0.09) with increased relative filling volume during the rapid filling period (80 ± 7 vs 75 ± 12%; p = 0.06) and decreased atrial contribution (17 ± 7 vs 22 ± 11%; p = 0.07). Stepwise discriminant analysis revealed that young age at diagnosis, syncope at diagnosis, reduced peak ejection rate, positive family history, reduced peak filling rate, increased relative filling volume by peak filling rate and concentric left ventricular hypertrophy were the most statistically significant (p = 0.0001) predictors of disease-related death (sensitivity 92%, specificity 76%, accuracy 77%, positive predictive value 25%). Discriminant analysis excluding the diastolic indexes, however, showed similar predictability (sensitivty 92%, specificity 76%, accuracy 78%, positive predictive value 26%). To obtain more homogenous groups for analysis, patients were classified as survivors (116) or electrically unstable (40), including sudden death, out-of-hospital ventricular fibrillation and nonsustained ventricular tachycardia during 48-hour ambulatory electrocardiography, and heart failure death or cardiac transplant (5). None of the diastolic indexes achieved statistical differences between the groups. Radionuclide assessment of diastolic function in HC did not improve predictability for 3-year mortality or contribute to the identification of patients at increased risk of sudden death.