Cardiac Arrhythmias and Defects in Systemic Sclerosis
Cardiac Arrhythmias and Defects in Systemic Sclerosis
In a study by Ferri et al., resting ECG showed one or more abnormal features in 22/53 (42%) SSc patients. Rhythm disturbances were demonstrated in 30% of patients, but when 24-h Holter ECG monitoring was performed, supraventricular arrhythmias were documented in 66% of SSc patients and ventricular arrhythmias were found in 90%, with multiform ventricular premature beats in 40%, pairs of runs of ventricular tachycardia in 28%, and one or more runs of ventricular tachycardia in 13%. The prevalence and severity of ventricular arrhythmias did not correlate with clinical variants or with other clinical symptoms and signs of the disease. Abnormal ventricular arrhythmias were more likely in patients with echocardiographic abnormalities, although ECG results were normal in about half of the patients who had ventricular arrhythmias. It is generally acknowledged that ventricular arrhythmias, particularly multiform and/or repetitive ventricular premature beats, have a poor prognosis when associated with impaired myocardial function. The high incidence of arrhythmias in this study may be explained by both the high sensitivity and lower specificity of Holter ECG.
A multicentre ambulatory ECG study in 183 SSc patients showed ventricular ectopy in 67% of patients, and this abnormality correlated with total mortality and sudden death. Episodes of ventricular tachycardia and supraventricular tachycardia were also observed in 7% and 21% of patients, respectively. Despite the very frequent occurrence of ventricular arrhythmias, sudden cardiac death is not very common in SSc. A large observational study reported sudden cardiac death in 18 (5%) of 391 deaths occurring in 1258 SSc patients, and severe cardiac arrhythmias with a poor prognosis were significantly more frequent in patients with concomitant skeletal and cardiac muscle involvement. In a meta-analysis evaluating 436 consecutive cases, Follansbee et al. reported the presence of an abnormal ECG in 46% of patients. Focusing the analysis on 100 selected SSc subjects presenting with evident cardiac abnormalities as assessed by a detailed cardiopulmonary evaluation or who died of more advanced disease, an abnormal ECG was found in 95% of cases.
Many electrophysiological abnormalities can be revealed only after careful and specific cardiac workup. Rokas et al. assessed SSc patients without evidence of myocardial involvement and arrhythmias by rest and 24-h Holter ECG, echocardiography and radionuclide ventriculography. They found one or more of significant supraventricular or ventricular tachyarrhythmia, sinus node dysfunction and atrioventricular conduction delay in 57% of the patients. The marked atrial conduction delay probably occurs because of depression of the conduction velocity of abnormal atrial fibres, changes in the resting membrane potential, the action potential amplitude or the maximal velocity of the action potential upstroke, which are all associated with depressed conduction velocity and abnormal excitability. This high prevalence in the absence of any clinical symptoms or signs on standard ECG highlights the need for complete investigation, even at an early stage of the disease, long before the clinical manifestations of scleroderma heart disease (SHD) have appeared.
Other parameters that can be evaluated in SSc patients during 24-h Holter ECG monitoring are heart rate variability (HRV) and heart rate turbulence (HRT). HRV is a measure of cardiovascular autonomic activity and its decrease after myocardial infarction is thought to be associated with increased cardiovascular risk. HRT describes a fluctuation during sinus cycle length that occurs after a ventricular premature beat. It is controlled by the autonomic nervous system and reflects baroreflex sensitivity. As observed in post-infarction studies, HRT impairment is an independent risk factor for malignant ventricular arrhythmia and sudden cardiac death. Bielous-Wilk et al. analysed 27 SSc patients without clinically evident heart disease and observed a significantly greater number of premature contractions (supraventricular and ventricular), indicating a possible arrhythmogenic substrate within myocardium. Four patients also manifested supraventricular tachycardia. Several studies demonstrated impairment of HRV in time and frequency domains as well as HRT, confirming that patients with SSc develop cardiac autonomic nervous system dysfunction. Moreover, HRT seems to be a potential useful tool for the identification of patients at risk for ventricular arrhythmia, and might be considered an independent risk factor for mortality in SSc, although further studies are warranted before recommending routine HRT measurement in all SSc patients.
Arrhythmias
In a study by Ferri et al., resting ECG showed one or more abnormal features in 22/53 (42%) SSc patients. Rhythm disturbances were demonstrated in 30% of patients, but when 24-h Holter ECG monitoring was performed, supraventricular arrhythmias were documented in 66% of SSc patients and ventricular arrhythmias were found in 90%, with multiform ventricular premature beats in 40%, pairs of runs of ventricular tachycardia in 28%, and one or more runs of ventricular tachycardia in 13%. The prevalence and severity of ventricular arrhythmias did not correlate with clinical variants or with other clinical symptoms and signs of the disease. Abnormal ventricular arrhythmias were more likely in patients with echocardiographic abnormalities, although ECG results were normal in about half of the patients who had ventricular arrhythmias. It is generally acknowledged that ventricular arrhythmias, particularly multiform and/or repetitive ventricular premature beats, have a poor prognosis when associated with impaired myocardial function. The high incidence of arrhythmias in this study may be explained by both the high sensitivity and lower specificity of Holter ECG.
A multicentre ambulatory ECG study in 183 SSc patients showed ventricular ectopy in 67% of patients, and this abnormality correlated with total mortality and sudden death. Episodes of ventricular tachycardia and supraventricular tachycardia were also observed in 7% and 21% of patients, respectively. Despite the very frequent occurrence of ventricular arrhythmias, sudden cardiac death is not very common in SSc. A large observational study reported sudden cardiac death in 18 (5%) of 391 deaths occurring in 1258 SSc patients, and severe cardiac arrhythmias with a poor prognosis were significantly more frequent in patients with concomitant skeletal and cardiac muscle involvement. In a meta-analysis evaluating 436 consecutive cases, Follansbee et al. reported the presence of an abnormal ECG in 46% of patients. Focusing the analysis on 100 selected SSc subjects presenting with evident cardiac abnormalities as assessed by a detailed cardiopulmonary evaluation or who died of more advanced disease, an abnormal ECG was found in 95% of cases.
Many electrophysiological abnormalities can be revealed only after careful and specific cardiac workup. Rokas et al. assessed SSc patients without evidence of myocardial involvement and arrhythmias by rest and 24-h Holter ECG, echocardiography and radionuclide ventriculography. They found one or more of significant supraventricular or ventricular tachyarrhythmia, sinus node dysfunction and atrioventricular conduction delay in 57% of the patients. The marked atrial conduction delay probably occurs because of depression of the conduction velocity of abnormal atrial fibres, changes in the resting membrane potential, the action potential amplitude or the maximal velocity of the action potential upstroke, which are all associated with depressed conduction velocity and abnormal excitability. This high prevalence in the absence of any clinical symptoms or signs on standard ECG highlights the need for complete investigation, even at an early stage of the disease, long before the clinical manifestations of scleroderma heart disease (SHD) have appeared.
Other parameters that can be evaluated in SSc patients during 24-h Holter ECG monitoring are heart rate variability (HRV) and heart rate turbulence (HRT). HRV is a measure of cardiovascular autonomic activity and its decrease after myocardial infarction is thought to be associated with increased cardiovascular risk. HRT describes a fluctuation during sinus cycle length that occurs after a ventricular premature beat. It is controlled by the autonomic nervous system and reflects baroreflex sensitivity. As observed in post-infarction studies, HRT impairment is an independent risk factor for malignant ventricular arrhythmia and sudden cardiac death. Bielous-Wilk et al. analysed 27 SSc patients without clinically evident heart disease and observed a significantly greater number of premature contractions (supraventricular and ventricular), indicating a possible arrhythmogenic substrate within myocardium. Four patients also manifested supraventricular tachycardia. Several studies demonstrated impairment of HRV in time and frequency domains as well as HRT, confirming that patients with SSc develop cardiac autonomic nervous system dysfunction. Moreover, HRT seems to be a potential useful tool for the identification of patients at risk for ventricular arrhythmia, and might be considered an independent risk factor for mortality in SSc, although further studies are warranted before recommending routine HRT measurement in all SSc patients.
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