Left ventricle filling abnormalities prior to and following treatment of thyrotoxicosis--is diastolic dysfunction implicated in thyrotoxic cardiomyopathy?

Despite cardiac failure being a well recognised complication of thyrotoxicosis, systolic function has generally been reported as maintained or enhanced. In this study, left ventricular diastolic function was assessed in 16 thyrotoxic patients and 18 age-matched controls by pulsed-Doppler echocardiography. Patients were re-studied after 3 and 12 months of treatment. Prior to treatment all standard Doppler-derived indices of diastolic function were significantly different to control (isovolumic relaxation time (IVRT) 63 +/- 18.9 vs 84.0 +/- 14.8 ms, peak early filling velocity (Emax) 79.2 +/- 15.2 vs 61.9 +/- 10.7 cm.s-1, peak atrial filling velocity (Amax) 68.2 +/- 17.9 vs 42.2 +/- 9.4 cm.s-1, deceleration of early filling (E/F slope) 6.1 +/- 1.8 vs 3.7 +/- 1.1 m.s-1, thyrotoxic vs control). However, these filling abnormalities appear likely to reflect the tachycardia and reduced systemic vascular resistance (SVR) found in the patients (heart rate 102 +/- 15 vs 76 +/- 9, SVR 874 +/- 207 vs 1293 +/- 362 dynes.s-1 x cm-5, both P < 0.001). After 3 months of treatment haemodynamics were similar in the two groups but filling remained abnormal in patients with a pattern suggesting increased transmitral pressure gradients (Emax 73.1 +/- 15.1 cm.s-1, Amax 55.8 +/- 19.2 cm.s-1, E/F slope 4.9 +/- 2.0 m.s-1, all P < 0.05 compared to controls).(ABSTRACT TRUNCATED AT 250 WORDS)