ARRHYTHMOGENIC RISK OF EXERCISE STRESS TESTING
Abstract:
Background and purpose: In the last two decades, the indication of exercise stress testing (ET) enlarged, being used for diagnostic purposes and the evaluation of the great majority of cardiovascular patients. In the same period, the prevalence of arrhythmias significantly increased in cardiovascular patients, supporting a reevaluation of the arrhythmogenic risk of exercise stress testing. Methods: There were studied 1110 consecutively exercise stress tests, indicated for diagnosis or evaluation. There were excluded the subjects with arrhythmias at rest, immediately before ET. In the present study, there were took into account tachyarrhythmias (except sinus tachycardia), but also conduction disturbances during and ten minutes after the ET and they were correlated with (some) cardiovascular risk factors, etiology of cardiovascular disease and left ventricular performance. Results: The studied group consisted in 1110 patients, 589 females and 521 males, aged of 55,25 +/- 9,78 years, diagnosed with ischemic heart disease (64,1%), dilated cardiomyopathy (4,1%), arrhythmias (8,92%) and healthy subjects (22,88%). A number of 421 of all patients were addressed to ET for diagnostic reason. Arrhythmias were registered during ET in 21,2% of all cases and after effort in 13,0% and conduction disturbances during ET and after effort in 2,2%. During exercise the arrhythmias were represented by ventricular premature beats (VPB) in 13%, ventricular tachycardia in 1,1%, supraventricular extrasystoles 6,7% and atrial fibrillation 0,4%. VPB weren’t significantly more frequent in ischemic heart disease (12,6% vs 10,6%, p=0,14), except old myocardial infarction (24,5% vs 10,7%, p<0,001) and they were registered in 48% of the patients with LVEF <40% (vs 11,7% patients without old myocardial infarction, p<0,005). The correlation with left ventricular performance was also supported by the high incidence of VPB seen in dilated cardiomyopathy (71,1%). For VPB correlations were also registered with dyslipidemia (8,7% vs 20%, p<0,005), smoking (12,1% vs 15,8%, p<0,15), hypertension (10,8% vs 19,7%, p<0,005), obesity (29,1% vs 9,8%, p<0,001). The presence of VPB immediate after exercise is considered to have an increased arrhythmogenic risk. VPB were more frequent registered in patients with ischemic heart disease (7% vs 1%, p<0,05), dyslipidemia (19,6% vs 8,1%, p<0,005) and hypertension (6% vs 0%). The small percent of the patients who presented ventricular tachycardia don’t offer the possibility of any correlation. In case of supraventricular extrasystoles, the only correlation was registered with LVEF (25% in patients with LVEF40%, p<0,005), which suggests that they represent a sign of depressed left ventricular systolic performance and increased mean atrial pressure. Conclusion: The arrhythmogenic risk of ET is low, being represented mainly by ventricular premature beats, correlated with left ventricular performance, old myocardial infarction and some cardiovascular risk factors. In turn, no cardiac arrhythmic death was registered during exercise stress testing.
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