Takotsubo syndrome tied to impaired LV contractility, shortened systolic period

Patients with Takotsubo syndrome (TTS), a reversible form of heart failure with incompletely understood pathophysiology, may exhibit reduced cardiac contractility, shortened systolic period, inefficient energetics, and prolonged active relaxation but unaffected diastolic passive stiffness, a study has shown.

In this study, the investigators recorded left ventricular (LV) pressure‒volume loops in 24 consecutive patients with TTS and in a control population of 20 individuals without cardiovascular diseases.

TTS was characterized by impaired LV contractility (end-systolic elastance, 1.74 vs 2.35 mm Hg/mL; p=0.024; maximal rate of change in systolic pressure over time, 1,533 vs 1,763 mm Hg/s; p=0.031; end-systolic volume at a pressure of 150 mm Hg, 77.3 vs 46.4 mL; p=0.002) and a shortened systolic period (286 vs 343 mg; p<0.001).

The pressure‒volume diagram, in response, shifted rightward, with significant increases in LV end-diastolic (p=0.031) and end-systolic (p<0.001) volumes, preserving LV stroke volume (p=0.370) despite a lower LV ejection fraction (p<0.001).

Diastolic function was associated with prolonged active relaxation (relaxation constant, 69.5 vs 45.9 ms; p<0.001; minimal rate of change in diastolic pressure, ‒1,457 vs ‒2,192 mm Hg/s; p<0.001), but diastolic stiffness was not altered during TTS (end-diastolic volume at a pressure of 15 mm Hg, 96.7 vs 109.0 mL; p=0.942).

Furthermore, mechanical efficiency substantially decreased during TTS (p<0.001) considering reduced stroke work (p=0.001), increased potential energy (p=0.036), and a similar total pressure‒volume relative to that of controls (p=0.357).

“These findings may suggest decreased phosphorylation of myofilament proteins, which represents a potential therapeutic target in TTS,” the investigators said.