Third degree heart block in acromegaly

Electrophysiological features in acromegaly: re-thinking the arrhythmic risk?

BACKGROUND

Acromegaly is disease associated with a specific cardiomyopathy. Hitherto, it has been widely understood that acromegaly carries an increased risk of arrhythmia.

PURPOSE

In this review we show that evidences are limited to a small number of case-control studies that reported increased rates of premature ventricular beats (PVB) but no more significant arrhythmia. In contrast, there are several studies that have reported impaired preclinical markers of arrhythmia, including reduced heart rate variability, increased late potentials, QT interval dispersion, impaired heart rate recovery after physical exercise and left ventricular dysynchrony. Whilst these markers are associated with an adverse cardiovascular prognosis in the general population, they do not have a high independent positive predictive accuracy for arrhythmia. In acromegaly, case reports have described sudden cardiac death, ventricular tachyarrhythmia and advanced atrio-ventricular block that required implantation of a cardio-defibrillator or permanent pacemaker. Treatment with somatostatin analogues can reduce cardiac dysrhythmia in some cases by reducing heart rate, PVBs and QT interval. Pegvisomant reduces mean heart rate. Pasireotide is associated with QT prolongation. In the absence of good quality data on risk of arrhythmia in acromegaly, the majority of position statements and guidelines suggest routine 12-lead electrocardiography (ECG) and transthoracic echocardiography (TTE) in every patient at diagnosis and then follow up dependent on initial findings.

[Heart arrhythmias and conduction disorders in patients with acromegaly: the role of cardiac magnetic resonance imaging]

Cardiovascular complications including arrhythmias and cardiac conduction disorders are one of the main reasons of high mortality rate in acromegaly, while they have not been well explored.

AIM

To estimate arrhythmias frequency in acromegaly, identify risk factors leading to the development of arrhythmia and cardiac conduction disorder, to determine the role of cardiac MRI in detecting structural and functional changes.

MATERIALS AND METHODS

A single-center prospective cohort study, which included 461 patients (151 men and 310 women) with acromegaly, was conducted. All the patients underwent a standard medical examination, including hormonal blood test, electrocardiogram, echocardiography, electrocardiogram daily monitoring. 18 patients with arrhythmias (11 men and 7 women) had cardiac MRI with gadolinium-based contrast.

RESULTS

The results of our research show high frequency of arrhythmias and cardiac conduction disorders in patients with acromegaly 42%. Most frequent kinds of arrhythmias and cardiac conduction disorders were sinus bradycardia 19.1% of the cases and conduction disorders of bundle branch blocks 14.5%. Men were more likely to suffer from arrhythmias and cardiac conduction disorders than women (54.2% and 37.4%, respectively,p=0.0005). Not acromegaly activity but duration of the disease was a main risk factor of arrhythmias and cardiac conduction disorders. Patients with arrhythmias had a long anamnesis of acromegaly (10 and 7 years, respectively, p=0.04). Meanwhile, cardiac conduction disorders were commonly observed in the patients who were treated with somatostatin analogs comparing to the patients who didnt undergo this therapy (50% and 38.6% respectively,p=0.004). We showed that 61% of patients with acromegaly and cardiac conduction disorders who underwent magnetic resonance imaging (MRI) had the signs of myocardial fibrosis. The value of the ejection fraction of the left ventricle according to MRI was higher than with echocardiography (p=0.04).

CONCLUSION

Arrhythmias and cardiac conduction disorders are often observed in patients with acromegaly even with remission of the disease. High risk group need careful diagnostic and monitoring approaches. Cardiac MRI is the gold standard for visualization of structural and morphological changes in the heart. Use of cardiac MRI in acromegalic patients expands our understanding of arrhythmias and cardiac conduction disorders in this disease. There are no specific laboratory markers of diffuse myocardial fibrosis, and the role of myocardial fibrosis in the occurrence of cardiac arrhythmias and conduction disorders needs further studying.

Malignant ventricular tachycardia in acromegaly: a case report

CONTEXT

In patients with acromegaly, cardiovascular complications are the main cause of death; sudden death has been associated with ventricular tachyarrhythmias. In other patients with life-threatening malignant ventricular tachyarrhythmias, surgical placement of an implantable cardioverter-defibrillator (ICD) has proved highly effective in reducing sudden death rates.

CASE REPORT

The present article reports the case of a 50-year-old male acromegalic patient who presented symptoms of syncope induced by ventricular tachycardia. An ICD was surgically implanted and a pituitary adenoma, which was responsible for the acromegaly, was completely removed in the same procedure. The surgery was successful and the ventricular arrhythmias were effectively terminated. During six months of follow-up, no documented arrhythmic episodes occurred.

CONCLUSION

In patients with acromegaly, malignant ventricular tachyarrhythmia might be effectively controlled by implantation of an ICD and surgical removal of the pituitary adenoma.

Late potentials and ventricular arrhythmias in acromegaly

BACKGROUND

Sudden death and increased prevalence of ventricular arrhythmias have already been described in acromegaly. Although late potentials (LPs) have been proved to be a new technique in detecting patients at risk for ventricular tachyarrhythmias its use in acromegaly is still unknown.

METHODS

We studied 70 acromegalic patients [32 males, 38 females; age 49+/-12 years (mean+/-S.D.)] and 70 control subjects age- and sex-matched [(35 males and 35 females; 46+/-12 years (mean+/-S.D.)]. Besides hormonal tests, we performed the following cardiovascular investigations: ECG, 24-h ECG Holter monitoring, echocardiography, and signal-averaged ECG (SAECG) time-domain analysis.

RESULTS

LPs occurrence was significantly higher in acromegalic patients as compared to the control group (22.9% vs. 2.9%; p=0.001). A greater duration of disease in patients with positive LPs compared to negative ones was pointed out (18 vs. 12 years; p=0.024). In the group of acromegalic patients with positive LPs we observed a significant association with premature ventricular complexes (PVCs) detected by means of 24-h Holter ECG recording (13 out of 15 patients: 86.7%; p=0.024). The positivity or negativity of LPs proved to be significantly associated with Lown scale PVC trends recorded by 24-h Holter ECG (p=0.014). In the group of patients with left ventricular hypertrophy a significant and pathological worsening of SAECG signals (QRS, LAS, RMS) was documented.

CONCLUSIONS

We observed a higher prevalence of LPs in acromegaly which significantly correlated with Lown scale of PVCs.