Elsevier

Heart Rhythm

Volume 5, Issue 8, August 2008, Pages 1111-1114
Heart Rhythm

Original-clinical
Persistent left ventricular dilatation in tachycardia-induced cardiomyopathy patients after appropriate treatment and normalization of ejection fraction

https://doi.org/10.1016/j.hrthm.2008.04.023Get rights and content

Background

Tachycardia-induced cardiomyopathy (TIC) seems to be a form of reversible cardiomyopathy. With recurrence, TIC can be more severe and may increase the risk for sudden cardiac death.

Objective

We postulate that negative remodeling persists even though ejection fraction (EF) normalizes after appropriate treatment in these patients.

Methods

We analyzed 2-dimensional echocardiographic parameters of 24 patients with TIC (male: 21; age: 64.1 ± 15.2 years; atrial arrhythmias: 92%) that improved significantly with treatment (mean time between pretreatment and posttreatment echocardiography: 14 ± 6 months) and compared them with that of age-, gender-, and ejection fraction–matched control subjects without a history of TIC.

Results

The majority of posttreatment echocardiographic parameters showed a significant improvement (P <.05) with treatment in patients with TIC, including left ventricular (LV) ejection fraction (31.2% ± 8.2% to 55.0% ± 5.7%) and LV end systolic volume index (55 ± 21 ml/m2 to 33 ± 13 ml/m2). There was no significant difference in LV end diastolic volume index (78 ± 22 ml/m2 to 72 ± 22 ml/m2, P = .15). However, when compared with age-, gender-, and ejection fraction–matched control subjects, posttreatment echocardiographic parameters in TIC patients showed significant differences (TIC vs control group) in LV end systolic volume index (33 ± 13 ml/m2 vs 22 ± 5 ml/m2), LV end diastolic volume index (72 ± 22 ml/m2 vs 51 ± 12 ml/m2), and cardiac index (2.6 ± 0.8 l/min/m2 vs 1.8 ± 0.6 l/min/m2).

Conclusion

Although the majority of echocardiographic parameters, including EF, improved significantly with treatment in TIC patients, LV dimensions and volumes remained significantly elevated when compared with control subjects, indicating persistence of negative LV remodeling, even after appropriate treatment and normalization of EF at a mean follow-up of 14 months.

Introduction

Tachycardia-induced cardiomyopathy (TIC) is defined as atrial or ventricular dysfunction caused by tachycardia that reverses with abolition of the tachycardia. Although the prevalence of TIC is not known, it is increasingly being recognized as an important subset of reversible cardiomyopathy.1, 2, 3 People with TIC seem to have better outcomes compared with those with dilated cardiomyopathies.2 Although any tachyarrhythmia can cause TIC, atrial fibrillation and frequent premature ventricular complexes (PVC) seem to be common causes of TIC. The incidence of TIC in patients who are referred for radiofrequency ablation for atrial fibrillation is 18% to 37%, and for frequent monomorphic PVCs is 30% to 37%.3, 4, 5, 6, 7 The pathophysiology behind TIC is not well understood. In most cases, ventricular function normalizes after the tachycardia is appropriately treated. This is usually documented clinically by 2-dimensional echocardiography that shows an improvement in the left ventricular (LV) ejection fraction (EF).1, 2, 3 However, patients who experience TIC may be prone to recurrence of LV systolic dysfunction if the same or another tachycardia occurs, and this dysfunction seems to occur more rapidly and to a more severe extent when compared with the first episode.4 Also, they may be prone to sudden cardiac death.4 Animal experiments with TIC models have also shown that the LV continues to be dilated even after the tachycardia has been abolished and the EF has normalized.5, 6 Based on these prior findings, we postulated that although patients with TIC have normalized EFs after treatment of the tachycardia, they continue to have dilated LVs. We sought to look at the echocardiographic parameters in TIC patients pretreatment and posttreatment and to compare them to age-, gender-, and EF-matched control subjects to evaluate for adverse remodeling even in the presence of a normal EF.

Section snippets

Methods

We retrospectively analyzed echocardiographic parameters of patients who presented to the electrophysiology service at the Krannert Institute of Cardiology and the Veterans Administration Medical Center in Indianapolis, Indiana, for atrial or ventricular tachyarrhythmias and reduced EFs (<45%). Only patients without any obvious cause for an active cardiomyopathy except for the tachyarrhythmia were included in the study. To be defined as responders to treatment, patients had to have symptomatic

Statistics

Continuous data were expressed as the mean ± standard deviation and were compared using the paired t-test. Interobserver and intraobserver reliabilities of LV echocardiography measurements were performed with the Pearson correlation coefficient. A value of P <.05 was considered statistically significant. All statistical analyses were performed with SPSS 15.0 (SPSS, Inc., Chicago, Illinois).

Results

The mean age of the TIC group was 64.1 ± 15.2 years (range 36 to 88 years). Atrial arrhythmias were present in 92% of the patients, and 8% had ventricular arrhythmias. Although 25% of patients had a history of coronary artery disease (CAD), their EFs were disproportionate to the coronary artery lesions and their EFs improved significantly after control of the tachycardia and without any intervention for CAD in the interim. A total of 46% of the patients underwent radiofrequency ablation,

Discussion

Previously, patients with TIC were believed to be “cured” of their cardiomyopathy once their EF had normalized after treating the tachycardia. We have for the first time clinically shown that there is persistent negative remodeling of the LV even after normalization of EF that persists at least 14 months after initiating treatment, as demonstrated by increased LVESD, LVSvol, and LVDvol when compared with age-, gender-, and EF-matched control subjects. These findings are consistent with those of

Limitations

This is a retrospective study. Heart rate measurements were made at the time of the echocardiograms and during follow-up, and may not be a true reflection of the average basal heart rates. Three patients had atrial fibrillation with controlled rate during follow-up. However, asymptomatic tachyarrhythmias in these patients cannot be ruled out. Six patients with TIC had underlying coronary artery disease. However, they did not undergo any invasive interventions for CAD between the pretreatment

Conclusions

Our study shows that patients with TIC continue to have persistent negative LV remodeling even after their EF has normalized with appropriate treatment. A larger prospective study with a longer follow-up is needed to evaluate the significance of these findings.

References (9)

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