Life in the fast lane: clinical and immuno-histological characteristics
of tachycardia-induced cardiomyopathy – a retrospective study on 684
patients
Abstract
Introduction: Tachycardia-induced cardiomyopathy (TCM) has been known
for decades as a reversible form of non-ischemic cardiomyopathy.
However, its mechanism and properties remain poorly understood. Methods:
This retrospective study investigated endomyocardial biopsy samples from
18 patients with TCM and compared them with samples from 170 patients
with dilated cardiomyopathy (DCM), and 496 patients with inflammatory
cardiomyopathy (ICM). Results: 684 patients with recent-onset heart
failure and reduced ejection fraction not caused by valvular or ischemic
heart disease were analyzed. In the TCM group, 81% were male, mean age
was 60±13 years, and 94% had heart failure symptoms ≥2 NYHA class. At
baseline (BL), 78% had atrial fibrillation/flutter, and 11%
inappropriate sinus tachycardia, heart rate was higher compared to DCM
and ICM patients (122±25 versus 78±21; p<0.001). Mean ejection
fraction at BL was lower compared to DCM and ICM (27±12% versus
39.0±14.6%; p=0.001), but improved significantly more during follow-up
(FU) (20% versus 6%; p<0.001). At FU, heart rate and
presence of sinus rhythm were similar in all groups. 69% of TCM
patients underwent electrical cardioversion or ablation. Compared with
DCM patients, TCM patients had a stronger myocardial expression of MHC
class II and an equal amount of infiltration with T-cells/macrophages.
Compared with ICM patients, the presence of T-cells/macrophages was
significantly lower in TCM. The marker of apoptosis (caspase 3) was
comparably elevated in TCM/ICM patients. Conclusion: TCM is
characterized by immuno-histological changes comparable to DCM except
for caspase 3 levels, which were similar to those in ICM.