Asymptomatic versus symptomatic episodes in patients with paroxysmal atrial fibrillation via long-term monitoring with implantable loop recorders.

BACKGROUND: The presentation of atrial fibrillation (AF) varies remarkably, from totally asymptomatic to symptomatic patients, while the same individual may present symptomatic and asymptomatic episodes. We aimed to identify electrocardiographic differences between symptomatic and asymptomatic episodes and to find parameters related to the appearance of symptoms. METHODS: Thirty consecutive patients (age 66.9±10years) with paroxysmal AF received an implantable loop recorder. Three types of episodes were defined: asymptomatic (ASx), symptomatic (Sx), and mixed asymptomatic-symptomatic (AS-Sx). The heart rate (HR) and heart rate variability (HRV) were recorded during the first 2min of each ASx or Sx episode, and during the first 2min of both the symptomatic and asymptomatic periods in AS-Sx. RESULTS: Eighty-two episodes from twenty-five patients were evaluated. Mean HR was 142.48±25.84bpm for Sx and 95.71±19.29bpm for ASx (p<0.001). Mean HRV was 92.62±42.29ms for Sx and 150.06±49.68ms for ASx (p<0.001). In AS-Sx, mean HR was 102.91±24.54bpm for the asymptomatic and 141.88±23.43bpm for the symptomatic period (p<0.001). Mean HRV was 173.55±61.30ms for the asymptomatic and 87.33±30.65ms for the symptomatic period (p=0.003). There were no significant correlations between patients' characteristics and the clinical presentation of the arrhythmia. CONCLUSIONS: The ASx were characterized by a lower HR and higher HRV compared to Sx. In As-Sx, the asymptomatic period was characterized by a lower HR and higher HRV compared to the symptomatic. These findings suggest a possible contribution of variations in the autonomic nervous system activity to the perception of the arrhythmia.

Changes in atrial electrical properties following cardioversion of chronic atrial fibrillation: relation with recurrence.

OBJECTIVE: To study the reversibility of atrial electrical remodeling and its relation with recurrence in post-conversion chronic atrial fibrillation (CAF) patients. METHODS: In 28 drug-free CAF patients (mean AF duration 41+/-39 months) electrically converted to sinus rhythm effective refractory period (ERP) at 500 ms, monophasic action potential at 90% of repolarization (MAPd90) at five cycle lengths (CL, 350, 400, 450, 500, 600 ms), and P wave duration were measured three times: within the interval 5-20 min post-conversion, 24 h and 1 month later. Fifteen subjects with no history of AF and normal atrial structure served as a control group. Patients were followed up for recurrence for 1 month; 12 relapsed. RESULTS: ERP changed from 205+/-20 to 243+/-31 to 241+/-24 ms (P<0. 001), attaining a level comparable to that of the controls (238+/-21 ms) within 24 h. MAPd90 significantly (P<0.001) increased (from 175+/-11 to 190+/-19 to 191+/-10 ms at CL 350 ms and 201+/-12 to 234+/-20 and 233+/-23 ms at CL 600 ms) also reaching control levels within 24 h. MAPd90 exhibited an abnormal adaptation to rate only in the first evaluation. P wave duration was prolonged (137+/-33 ms) and exhibited a slower course of shortening (130+/-32 to 123+/-27 ms, P<0.001), reaching control levels within 1 month. Patients with higher values of MAPd90 at CL 350 in the immediate post-conversion period were more likely to relapse (P<0.005). CONCLUSIONS: ERP and repolarization shortening as a result of CAF are reversed within 24 h after conversion, while P wave duration reduces more slowly. Post-conversion MAPd90 values contain prognostic information for recurrence.

Relation of autonomic modulation to recurrence of atrial fibrillation following cardioversion.

The aim of this study was to investigate the time course of changes in autonomic nervous system activity in patients with long-standing atrial fibrillation (AF) following internal electrical conversion to sinus rhythm and to look for differences between patients who do and do not relapse. Time-domain indexes of heart rate variability were calculated from 24-hour Holter recordings on the day of conversion and 1 day and 1 month afterward for 22 patients with chronic (> 3 months) AF. Ten healthy subjects served as a control group. During the day of cardioversion the mean RR interval and its circadian variation differed significantly between controls and patients. The mean values of successive RR intervals that deviated by > 50% from the prior RR interval and the root-mean-square of successive RR interval differences--indexes of vagal modulation--were initially significantly higher in patients than in controls but showed a decrease (p < 0.05) by the second day (from 12.4 +/- 7% to 8.1 +/- 5% to 7.3 +/- 5% and from 49 +/- 9 to 39 +/- 12 to 41 +/- 11 ms, respectively) to levels similar to those of the controls (7.6 +/- 5% and 40 +/- 17 ms, respectively). Only these 2 indexes contained significant prognostic information about relapse: patients who later relapsed had higher initial values than those who did not, and these values remained high during the 2 days after conversion. In conclusion, this study provides data confirming that spontaneous chronic AF in humans results in a significant increase in vagal tone that is reversed with time after restoration of sinus rhythm. Persistently higher values of vagal tone are observed in patients who relapse, and are probably a predictor for recurrence.

Low-dose amiodarone versus sotalol for suppression of recurrent symptomatic atrial fibrillation.

To compare the safety and efficacy of amiodarone and sotalol in the treatment of patients with recurrent symptomatic atrial fibrillation (AF), 70 patients were entered into a randomized, double-blind study. Of these, 35 received amiodarone and 35 sotalol. There were no significant differences in baseline clinical characteristics between groups. Patients with ejection fraction < 40% or clinically significant heart disease were excluded. Patients randomized to amiodarone began with 800 to 1,600 mg/day for 7 to 14 days orally. After the initial loading phase, the drug dose was tapered to maintenance levels over 7 to 12 days; thereafter, therapy was generally maintained at a dosage of 200 mg/day. The sotalol dosage was 80 to 360 mg twice daily, as tolerated. Follow-up clinical evaluations were conducted at 1, 2, 4, 6, 9, and 12 months. The proportion of patients remaining in sinus rhythm on each agent was calculated for the 2 groups using the Kaplan-Meier method. Ten of the 35 patients who were taking amiodarone developed AF during the 12-month observation period, compared with 21 of the 35 who were taking sotalol (p = 0.008). No significant effect of sex, age, left atrial size, or type of AF could be detected that increased the risk of development of AF. We conclude that both amiodarone and sotalol can be used for the maintenance of normal sinus rhythm in patients with recurrent symptomatic AF but that amiodarone is the more effective of the 2 drugs for this purpose.

Left ventricular diastolic filling changes during dipyridamole-induced ischaemia. An echo-Doppler study.

OBJECTIVE: To evaluate the usefulness of the Doppler assessment of left ventricular diastolic functioning during dipyridamole-induced ischaemia in patients with coronary artery disease (CAD). METHODS: We studied 28 patients with angiographically proven CAD [18 men, aged 62 +/- 7 years (mean +/- SD)] and 18 normal subjects (12 men, aged 59 +/- 7.5 years). Two-dimensional and transmitral flow Doppler echocardiography studies were performed at baseline and after intravenous administration of a high dose of dipyridamole (0.84 mg/kg during 10 min). Left ventricular wall motion was evaluated by two-dimensional Doppler echocardiography, with the left ventricle divided into a 16-segment model, whereas peak velocities of early and late diastolic flow, the early:late diastolic flow ratio and the deceleration rate of early diastolic flow were determined from transmitral flow Doppler echocardiography. RESULTS: Sixteen patients developed new wall-motion abnormalities (WMA), whereas the remaining 12 patients and the controls did not. Multivariate logistic regression analysis was performed to identify which of the parameters had independent diagnostic value for revealing CAD. WMA was entered at the first step and yielded a 57% sensitivity and 100% specificity; the changes in deceleration rate were entered as the second step, which improved the sensitivity to 85.5%, and reduced the specificity to 83% and raised the overall accuracy to 85% from 70% for WMA alone. More specifically, the sensitivity improved from 37.5, 63.5 and 65.5% to 62.5, 91 and 100%, respectively, for patients with one-, two- and three-vessel disease. The cut-off value of the change in deceleration rate was 7%. CONCLUSIONS: Patients could be classified as having CAD either if they developed new WMA or if the deceleration rate of early diastolic flow during dipyridamole-stress echocardiography increased by more than 7% compared with the rest value.

Spectral analysis of heart rate variability during tilt-table testing in patients with vasovagal syncope.

Spectral analysis of heart rate variability was used to assess changes in autonomic function in 44 patients with vasovagal syndrome and 20 normal controls before and during postural tilt and to attempt to relate such changes to specific types of haemodynamic response to tilt. Frequency domain measurements of the high (HF) and low (LF) frequency bands and the ratio LF/HF were derived from Holter recordings, computed by Fast Fourier Analysis for 4 min intervals immediately before tilt testing, immediately after tilting and just before the end of the test. In the syncopal patients the mean values of LF and HF decreased significantly in response to tilting, while the LF/HF ratio remained constant. All parameters showed a statistically significant increase just before the onset of syncope. In the control group there was an increase in the LF and LF/HF ratio and a decrease in the HF immediately after tilting. The three subgroups of patients had similar patterns of changes in autonomic activity. The results of this study show that syncopal patients have a different pattern of response to the tilting test. The pathological mechanism leading to vasovagal syncope appears to be independent of the specific type of haemodynamic response to tilt testing.

Aortic atherosclerotic lesions in the thoracic aorta detected by multiplane transesophageal echocardiography as a predictor of coronary artery disease in elderly patients.

BACKGROUND: The presence of atherosclerotic lesions in the thoracic aorta by transesophageal echocardiography (TEE) appears to be a marker for the presence of significant coronary artery disease (CAD) in the general population. HYPOTHESIS: We investigated whether atherosclerotic lesions in the thoracic aorta, by multiplane TEE, could be a marker for CAD in elderly patients. METHODS: In all, 127 patients (67 men, 60 women, aged 68 +/- 13 years), underwent a TEE study with imaging of the thoracic aorta and cardiac catheterization with coronary angiography. The presence of a distinct, linear, or focal, highly echogenic mass protruding into the vessel lumen was the criterion for the diagnosis of atherosclerotic plaque. RESULTS: Atherosclerotic lesions were found in 30 of 36 patients (83.3%) with and in 20 of 91 (22%) without CAD. Of the 41 patients > or = 70 years, atherosclerotic lesions were detected in 14 of 17 (82.3%) with and in 13 of 24 patients (54%) without CAD. The sensitivity, specificity, and positive and negative predictive values in this group were 82.3, 46, 52, and 78.6%, respectively. Multivariate logistic regression analysis revealed that in patients aged > or = 70 years only advanced atherosclerotic lesions were independent predictors of significant CAD. However, the high negative predictive value of the method indicates that the absence of aortic plaque is a strong predictor of the absence of CAD. CONCLUSIONS: The presence of atherosclerotic lesions in the thoracic aorta is a strong predictor of CAD only in patients < 70 years old. However, the negative predictive value of the method is high for all patients regardless of age.

The role of the post-cardioversion time course of hs-CRP levels in clarifying the relationship between inflammation and persistence of atrial fibrillation.

OBJECTIVES: Although recent studies suggest that inflammation is involved in the pathogenesis of atrial fibrillation (AF), it remains controversial whether it is a consequence or a cause of the arrhythmia. DESIGN: Prospective study. SETTING: Tertiary referral centre. PATIENTS AND INTERVENTIONS: In 52 patients with persistent AF lasting >3 months, high-sensitivity C-reactive protein (hs-CRP) was measured before and after electrical cardioversion. MEASUREMENTS AND RESULTS: All patients were successfully cardioverted to sinus rhythm (SR), but the recurrence rate was 23% at 1 month. Baseline hs-CRP was higher in patients with AF recurrence than in those who remained in SR (0.5 (SD 0.18) mg/dl vs 0.29 (SD 0.13) mg/dl, respectively, p<0.001). Similarly, arrhythmia recurrence was associated with greater left atrial diameters (45.4 (SD 3.3) mm vs 40.7 (SD 3.1) mm, respectively, p<0.001). However, logistic regression analysis showed that hs-CRP was the only independent predictor for AF recurrence (p<0.001). Additionally, patients who were in SR on final evaluation had significantly lower hs-CRP levels than at baseline (0.10 (SD 0.06) mg/dl vs 0.29 (SD 0.13) mg/dl, respectively, p<0.001), while those who experienced AF recurrence had similar values on final and on initial evaluation (0.56 (SD 0.24) mg/dl vs 0.50 (SD 0.18) mg/dl, respectively, p = 0.42). CONCLUSION: High levels of hs-CRP are associated with an increased risk of AF recurrence after cardioversion. The restoration and maintenance of SR result in a gradual decrease of hs-CRP while AF recurrence has a different effect, suggesting that inflammation is a consequence, rather than a cause, of AF.

Spectral analysis of heart rate variability before and during episodes of nocturnal ischaemia in patients with extensive coronary artery disease.

Spectral analysis of heart rate variability was used to assess autonomic nervous system activity associated with episodes of nocturnal myocardial ischaemia in 32 patients (20 men, age 58 +/- 9 years) with extensive coronary artery disease. Twenty-four hour Holter tape recordings were analysed and spectral indexes of heart rate variability were computed by fast Fourier analysis on 2 min segments covering the period from 10 min before to 10 min after each nocturnal ischaemic episode, defined as ST segment depression > or = 1 mm lasting at least 4 min. Spectral power was measured at low frequencies (LF: 0.06-0.10 Hz) and high frequencies (HF: 0.15-0.40 Hz) and the ratio LF/HF was calculated. RESULTS. A total of 30 episodes of nocturnal ischaemia were analysed. High frequency spectral power showed a clear decrease during the 10 min before the onset of ischaemia, remained steady until the end of the episode, and returned to normal by 6 min after. Low frequency spectral power fluctuated throughout the ischaemic episodes with no clear pattern of variation. The low/high frequency ratio reflected mainly the changes in high frequency. CONCLUSIONS. Sympathetic predominance due to para-sympathetic withdrawal is the principal change in autonomic nervous system activity associated with episodes of nocturnal ischaemia.

Reproducibility of tilt table testing in patients with vasovagal syncope and its relation to variations in autonomic nervous system activity.

To assess the variability of head-up tilt table testing, 35 patients with vasovagal syncope, shown by a positive tilt table test, underwent a second test 1 week later. Also, on the day before each test, spectral and time-domain indexes of heart rate variability were derived from Holter recordings to examine the stability of autonomous nervous system activity in these patients. Fifteen healthy volunteers served as a control group and also underwent two tilt table tests with prior Holter monitoring. Twenty-one (60%) of the 35 patients had a second positive test. None of the patients in the control group experienced syncope during either of the tests. The heart rate variability measures in the control group varied slightly from 1 day to the other, in contrast to the syncopal patients, where only low frequency spectral power and the mean of all 5-minute standard deviations of RR intervals showed comparable behavior. The indexes which reflect parasympathetic activity exhibited significant fluctuations in the syncopal patients. These fluctuations were due entirely to the patients who did not reproduce the outcome of the tilt table test, where high parasympathetic tone was associated with the positive test and normal parasympathetic tone with the negative test. In contrast, the patients with two positive tests had high parasympathetic tone during both test periods, with low individual variability. In conclusion, patients with vasovagal syncope show variations in vagal autonomic tone and appear to be more prone to syncope when their parasympathetic tone is elevated.