Mechanism of syncope in patients with bundle branch block and negative electrophysiological test.

BACKGROUND: In patients with syncope and bundle branch block (BBB), syncope is suspected to be attributable to a paroxysmal atrioventricular (AV) block, but little is known of its mechanism when electrophysiological study is negative. METHODS AND RESULTS: We applied an implantable loop recorder in 52 patients with BBB and negative conventional workup. During a follow-up of 3 to 15 months, syncope recurred in 22 patients (42%), the event being documented in 19 patients after a median of 48 days. The most frequent finding, recorded in 17 patients, was one or more prolonged asystolic pause mainly attributable to AV block; the remaining 2 patients had normal sinus rhythm or sinus tachycardia. The onset of the bradycardic episodes was always sudden but was sometimes preceded by ventricular premature beats. The median duration of the arrhythmic event was 47 seconds. An additional 3 patients developed nonsyncopal persistent III-degree AV block, and 2 patients had presyncope attributable to AV block with asystole. No patients suffered injury attributable to syncopal relapse. CONCLUSIONS: In patients with BBB and negative electrophysiological study, most syncopal recurrences have a homogeneous mechanism that is characterized by prolonged asystolic pauses, mainly attributable to sudden-onset paroxysmal AV block.

Role of autonomic reflexes in syncope associated with paroxysmal atrial fibrillation.

OBJECTIVES: The purpose of this study was to evaluate the role of autonomic reflexes in the genesis of syncope associated with the onset of paroxysmal atrial fibrillation. BACKGROUND: Syncope associated with paroxysmal atrial fibrillation has been interpreted as an ominous finding predictive of rapid ventricular rates. However, various mechanisms may be involved when heart rate is not particularly high. METHODS: Forty patients (age 60 +/- 14 years, 20 men, 20 women) with syncope and atrial fibrillation were compared with atrial fibrillation without syncope. Carotid sinus massage and head-up tilt testing (at 60 degrees for 60 min at baseline and during isoproterenol infusion) were performed during sinus rhythm. A positive response was defined as the induction of syncope. Atrial fibrillation was also induced on a tilt table at 60 degrees by means of short bursts of atrial pacing. RESULTS: Results of carotid sinus massage were positive in 15 (37%) of 40 patients but in no control subjects (p = 0.002). Head-up tilt test findings were positive in 25 (66%) of 38 patients and in 2 (12%) of 16 control subjects (p = 0.0004). The induction of atrial fibrillation in the upright position elicited syncope in 16 (42%) of 38 patients but in none of 16 control subjects (p = 0.001). At the beginning of atrial fibrillation, systolic blood pressure was lower in patients than in control subjects (88 +/- 32 vs. 127 +/- 32 mm Hg), whereas mean heart rate was similar (142 +/- 35 vs. 134 +/- 25 beats/min). The correlation between heart rate and systolic blood pressure was weak (r = 0.35), and in five patients syncope occurred at a heart rate < or = 130 beats/min. At the time of syncope, heart rate decreased (-12 +/- 21 beats/min) in patients with induced syncope, whereas it remained unchanged in patients without induced syncope (+1 +/- 17 beats/min, p = 0.04) or slightly increased in control subjects (+9 +/- 21 beats/min, p = 0.009). CONCLUSIONS: Patients with syncope associated with paroxysmal atrial fibrillation are predisposed to an abnormal neural response during both sinus rhythm and arrhythmia. In some patients the onset of atrial fibrillation triggers vasovagal syncope.

Efficacy and safety of out-of-hospital self-administered single-dose oral drug treatment in the management of infrequent, well-tolerated paroxysmal supraventricular tachycardia.

OBJECTIVES: We tested the efficacy of two drug treatments, flecainide (F) and the combination ofdiltiazem and propranolol (D/P), administered as a single oral dose for termination of the arrhythmic episodes. BACKGROUND: Both prophylactic drug therapy and catheter ablation are questionable as first-line treatments in patients with infrequent and well-tolerated episodes of paroxysmal supraventricular tachycardia (SVT). METHODS: Among 42 eligible patients (13% of all screened for SVT) with infrequent (< or =5/year), well-tolerated and long-lasting episodes, 37 were enrolled and 33 had SVT inducible during electrophysiological study. In the latter, three treatments (placebo, F, and D/P) were administered in a random order 5 min after SVT induction on three different days. RESULTS: Conversion to sinus rhythm occurred within 2 h in 52%, 61%, and 94% of patients on placebo, F and D/P, respectively (p < 0.001). The conversion time was shorter after D/P (32 +/- 22 min) than after placebo (77 +/- 42 min, p < 0.001) or F (74 +/- 37 min, p < 0.001). Four patients (1 placebo, 1 D/P, and 2 F) had hypotension and four (3 D/P and 1 F) a sinus rate <50 beats/min following SVT interruption. Patients were discharged on a single oral dose of the most effective drug treatment (F or D/P) at time of acute testing. Twenty-six patients were discharged on D/P and five on F. During 17 +/- 12 months follow-up, the treatment was successful in 81% of D/P patients and in 80% of F patients, as all the arrhythmic episodes were interrupted out-of-hospital within 2 h. In the remaining patients, a failure occurred during one or more episodes because of drug ineffectiveness or drug unavailability. One patient had syncope after D/P ingestion. During follow-up, the percentage of patients calling for emergency room assistance was significantly reduced as compared to the year before enrollment (9% vs. 100%, p < 0.0001). CONCLUSIONS: The episodic treatment with oral D/P and F, as assessed during acute testing, appears effective in the management of selected patients with SVT. This therapeutic strategy minimizes the need for emergency room admissions during tachycardia recurrences.

Diagnostic value of history in patients with syncope with or without heart disease.

OBJECTIVES: We sought to establish what historical findings are predictive of the cause of syncope. BACKGROUND: The clinical features of the various types of syncope have not been systematically investigated. METHODS: Three hundred forty-one patients with syncope were prospectively evaluated. Each patient was interviewed using a standard questionnaire. A cause of syncope was assigned using standardized diagnostic criteria. RESULTS: A cardiac cause of syncope was established in 23% of the patients, a neurally mediated cause in 58% and a neurologic or psychiatric cause in 1%, and in the remaining 18%, the cause of syncope remained unexplained. In a preliminary analysis including age, gender and the presence of suspected or certain heart disease after the initial evaluation, only heart disease was an independent predictor of a cardiac cause of syncope (odds ratio 16, p = 0.00001), with a sensitivity of 95% and a specificity of 45%. In contrast, the absence of heart disease allowed us to exclude a cardiac cause of syncope in 97% of the patients. In patients with certain or suspected heart disease, the most specific predictors of a cardiac cause were syncope in the supine position or during effort, blurred vision and convulsive syncope. Significant and specific predictors of a neurally mediated cause were time between the first and last syncopal episode >4 years, abdominal discomfort before the loss of consciousness and nausea and diaphoresis during the recovery phase. In the patients without heart disease, palpitation was the only significant predictor of a cardiac cause. CONCLUSIONS: The presence of suspected or certain heart disease after the initial evaluation is a strong predictor of a cardiac cause of syncope. A few historical findings are useful to predict cardiac and neurally mediated syncope in patients with and without heart disease.

Long-term outcome of paced and nonpaced patients with severe carotid sinus syndrome.

The natural history of patients with severe carotid sinus syndrome, and the efficacy of permanent pacemaker treatment are not clearly known. A randomized treatment/nontreatment prospective study was performed in 60 patients affected by carotid sinus syndrome whose symptoms were judged to involve risk of major trauma or interfered with their daily activity. They were randomly assigned to 2 groups: 28 patients to no therapy (nonpacing group), and 32 to VVI (n = 18) or DDD (n = 14) pacemaker implant (pacing group). Syncope recurred in 16 patients (57%) of the nopacing group (mean follow-up 36 +/- 10 months) and in only 3 (9%) of the pacing group (mean follow-up 34 +/- 10 months) (p = 0.0002); moreover, 19 (68%) in the nonpacing group needed a secondary pacemaker implant because of the severity of symptoms. The actuarial rate of absence of syncopal recurrence after 1, 2, 3 and 4 years was 64, 54, 38 and 38%, respectively, for the nonpacing group, and 100, 97, 93 and 84%, respectively, for the pacing group (p = 0.0001). The actuarial rate of absence of minor symptoms after 1, 2, 3 and 4 years was 21, 14, 7 and 7%, respectively, for the nonpacing group and 66, 43, 27 and 27%, respectively, for the pacing group (p = 0.002). Reproducibility of carotid sinus reflex was tested after 15 +/- 8 months in 54 patients; an abnormal response to carotid sinus massage persisted in all 54. In conclusion, symptoms recur in most patients with untreated carotid sinus syndrome, and pacing is a useful therapy for preventing recurrences.

Progression of permanent atrial fibrillation after atrioventricular junction ablation and dual-chamber pacemaker implantation in patients with paroxysmal atrial tachyarrhythmias.

Among 63 patients affected by symptomatic drug refractory paroxysmal atrial fibrillation who had undergone atrioventricular junction ablation and dual-chamber pacemaker implantation, the actuarial estimate of progression of permanent atrial fibrillation was 22%, 40%, and 56% respectively, 1, 2, and 3 years after ablation. A stratification of the risk of development of permanent atrial fibrillation was obtained on the basis of several clinical variables.

Effects of left ventricular pacing on cardiac performance and on quality of life in patients with drug refractory heart failure.

We assessed the effects of left ventricular pacing on echocardiographic and clinical parameters in 13 consecutive patients with heart failure and bundle branch block by means of a controlled acute and medium-term evaluation. Left ventricular pacing induced a significant improvement in left ventricular ejection fraction, Minnesota Living with Heart Failure Questionnaire score, New York Heart Association class, and 6-minute walking test compared with sinus rhythm or right ventricular pacing.

Follow-up of asystolic episodes in patients with cardioinhibitory, neurally mediated syncope and VVI pacemaker.

The occurrence rate of spontaneous asystolic episodes during long-term follow-up in patients with abnormal asystolic responses induced by means of vasovagal maneuvers was evaluated. The heart rate of 23 patients (mean age 64 +/- 12 years; 6 women and 17 men) affected by neurally mediated syncope (mean 4.3 +/- 4.9 episodes) was continuously monitored by a specially designed implanted pacemaker able to detect and store in its memory all asystolic episodes lasting 3 to 6 or > 6 seconds. Asystolic, neurally mediated syncope was diagnosed when a reflex asystole of > 3 seconds was induced during carotid sinus massage (n = 22), eyeball compression test (n = 3) or head-up tilt test (n = 2). During a total of 357 months (mean 15 +/- 7) of monitoring, asystolic episodes occurred in 17 patients (74%): 1,765 episodes of 3- to 6-second (median 3) duration occurred in 14 patients, and 47 episodes of > 6-second (median 2) duration occurred in 11. The actuarial estimates of occurrence of asystolic episodes of > 3 and > 6 seconds were 82 and 53%, respectively, after 2 years of follow-up. Only 12 episodes of 3 to 6 seconds (0.7%), and 20 episodes of > 6 seconds (43%) resulted in presyncopal or syncopal symptoms. Thus, an asystolic response to vasovagal maneuvers predicts the occurrence of spontaneous asystolic episodes during follow-up. With few exceptions, spontaneous episodes are asymptomatic and their incidence is low.

Influence of atrioventricular junction radiofrequency ablation in patients with chronic atrial fibrillation and flutter on quality of life and cardiac performance.

The purpose of this study was to evaluate the effects of atrioventricular junction radiofrequency ablation on the quality of life, exercise performance, and echocardiographic parameters in 23 patients with chronic, severely symptomatic, drug-refractory atrial fibrillation or flutter. Initially, patients were randomized to receive ablation plus pacemaker therapy (n = 12) or pacemaker therapy alone (n = 11). After 15 days, palpitations decreased by 92% and 37% (p = 0.004), rest dyspnea by 79% and 40% (p = NS), effort dyspnea by 65% and 30% (p = 0.03), exercise intolerance by 54% and 17% (p = 0.005), and asthenia by 67% and 31% (p = 0.02) in the 2 groups, respectively. At the end of this short-term study, control patients also underwent ablation therapy, and a 3-month intrapatient follow-up study was performed in 22 patients. New York Heart Association functional class > or = 3 was present in 14 patients (64%) before, but in only 3 patients (14%) after ablation therapy (p = 0.002); specific activity scale functional class > or = 3 was present in 9 patients (41%) before, but in only 5 (23%) after ablation therapy (p = NS). Exercise duration during standardized stress testing increased by a mean of 63 +/- 93 seconds (15% increase) (p = 0.001). In the 9 patients with depressed left ventricular systolic function, echocardiographic fractional shortening increased by 34% (from 23 +/- 5% to 31 +/- 9%) (p = 0.003). In the remaining 13 patients with normal systolic function, fractional shortening decreased by 10% (from 40 +/- 5% to 36 +/- 6%) (p = 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Mechanisms of syncope caused by transient bradycardia and the diagnostic value of electrophysiologic testing and cardiovascular reflexivity maneuvers.

Transient bradycardia may be intrinsic because of sinus node or atrioventricular (AV) conduction abnormalities, or extrinsic because of abnormal vagal reflex. Twenty-five consecutive patients, referred to us for study of unexplained syncope, who, during electrocardiographic monitoring, had a documented episode of intermittent bradycardia that caused syncope, underwent a full electrophysiologic study, carotid sinus massage, and the head-up tilt test. A prolonged ventricular asystole (5 to 20 seconds) was documented during syncope in all patients: sinus arrest in 13, AV block in 7, sinus arrest plus AV block in 3, and asystolic pause during atrial fibrillation in 2. Abnormal electrophysiologic findings suggested the correct diagnosis in 6 patients (24%): block within the bundle of His in 5 and sick sinus syndrome in 1. An abnormal response to carotid sinus massage or to the head-up tilt test suggested a neurally mediated mechanism in 17 patients (68%). Overall, electrophysiologic study and vasovagal maneuvers were able to identify the mechanism of spontaneous syncope in 23 patients (92%). Thus, in patients affected by syncope due to transient bradycardia, the most likely mechanism of syncope is neurogenic, whereas it is cardiogenic only in a few instances. Electrophysiologic testing, carotid sinus massage, and the head-up tilt test can identify most of these patients. Conversely, when all these tests are negative, it is unlikely that transient bradycardia is the cause of syncope. Because of the different mechanisms involved, electrophysiologic study and vasovagal maneuvers are complementary diagnostic tools.

A controlled trial of acute and long-term medical therapy in tilt-induced neurally mediated syncope.

To study the efficacy of medical treatment for preventing syncopal recurrences in patients affected by tilt-induced neurally mediated syncope, a randomized placebo-treatment prospective study was performed in 30 patients (10 men and 20 women, mean age 42 +/- 21 years) who had syncope reproduced in 2 consecutive head-up tilt-table tests without pharmacologic intervention (n = 20) or during isoproterenol infusion (n = 10). Patients were randomly assigned to 2 groups: 15 to placebo, and 15 to drug therapy (determined on the basis of serial pharmacologic tilting tests). Therapy was either atenolol (n = 7), dihydroergotamine (n = 2), domperidone (n = 2), cafedrine (n = 1), or elastic compression stockings, alone or in association with drugs (n = 3). During a mean of 10 +/- 7 months of follow-up, syncope recurred in 3 patients (20%) in the treatment group and in 4 (27%) in the placebo group; actuarial rates of absence of syncopal recurrences after 20 months were 70 and 67%, respectively. Thus, the outcome of either treated or untreated patients was favorable (with a low recurrence rate of syncope), and the usefulness of tilting-guided medical therapy remains uncertain.

Effects of chronic vasodilator therapy to enhance susceptibility to vasovagal syncope during upright tilt testing.

To evaluate the effect of chronic vasodilator therapy on susceptibility to vasovagal syncope, 45 patients with syncope and a positive response to tilt testing were randomly assigned to continue or to discontinue vasodilators. The study result demonstrated that chronic vasodilator therapy enhances susceptibility to vasovagal reaction during upright tilt testing.

Carotid sinus syncope: the most frequent neurally mediated syncope in the elderly.

The present work reviews current literature and the authors' experience of carotid sinus syndrome (CSS), which is considered to be the most common cause of neurally mediated acute disorders of consciousness in the elderly. Although no definitive consensus about its nosology has yet been reached, most groups agree that three features fulfill the diagnosis: anamnestic presence of syncope or its minor equivalents, and their reproduction by carotid sinus massage associated with defined values of cardioinhibition or vasodepression or both. The technique for performing carotid sinus massage used by the authors is described; this manoeuvre seems very safe and reproducible as long as simple rules are followed, and it allows the classification of CSS types. The treatment of CSS is varied, according to several factors. No pharmacological therapy has yet been demonstrated to be effective. While severe cardioinhibitory forms require an appropriate pacing, vasodepressive ones and types with only minor symptoms show a more favourable natural history. Pacing is advised in mixed CSS with either frequent and invalidating relapses, or 'high risk' attacks (severe, abrupt, with major traumas, etc.). Finally, the protocol for choosing the adequate mode of pacing is illustrated. In most cases VVI is sufficient, but the decision requires a careful individual examination.

[Comparison of clinical and electrophysiologic characteristics of patients with occult and manifest atrioventricular accessory pathway]. / Confronto delle caratteristiche cliniche ed elettrofisiologiche dei pazienti con via accessoria atrioventricolare occulta e manifesta.

BACKGROUND: It is current opinion that concealed and manifest accessory pathways (APs) are indistinguishable with respect to their location and contribution to orthodromic reciprocating tachycardias. The aim of this study was to compare clinical and electrophysiological characteristics of two groups of patients. METHODS: Between January 1999 and June 2000, 42 consecutive patients underwent radiofrequency catheter ablation for paroxysmal atrioventricular reciprocating tachycardia attributable to a concealed AP. Their clinical and electrophysiological characteristics were compared with a group of 48 consecutive patients with manifest AP and supraventricular tachyarrhythmias. RESULTS: There were no differences regarding gender, the prevalence of heart disease and the age of onset of symptomatic tachycardias between the two groups. Compared to those with a manifest AP, the patients presenting with a tachyarrhythmia due to a concealed AP were older (48 +/- 15 vs 40 +/- 16 years, p < 0.05) and had a longer history of tachyarrhythmias (22 +/- 16 vs 13 +/- 13 years, p < 0.05). Atrial fibrillation was more frequent in patients with a manifest AP than in patients with a concealed AP (50 vs 9.5% respectively, p = 0.02). Atrioventricular reciprocating tachycardia was a cause of more hospitalizations (76 vs 35%, p = 0.01) and episodes of pre-syncope (47 vs 22%, p < 0.05) in the group of patients with a concealed AP. The anatomical site of concealed and manifest APs was significantly different: concealed APs were more frequently localized in the left side (93% left, 7% right), while manifest APs were seen in the left side in 64% of cases, in the right side in 29% and in the posteroseptal left + right region in 7% of cases. The retrograde electrophysiological properties and the inducibility of other types of reentrant arrhythmias were similar. Catheter ablation was similarly successful regardless of whether the AP was concealed or manifest, the rates of success being 91 and 88% respectively at the first attempt and with a similar number of energy applications (7 +/- 7 vs 10 +/- 9, p = NS). At a second attempt, the procedure was successful in 100 and 98% of cases respectively. Periprocedural complications occurred in 5% of patients with a concealed (1 ventricular fibrillation, 1 cerebral transient ischemic attack) and in 8% of patients with a manifest AP (2 pericardial effusion, 1 transient atrioventricular block, 1 anginal attack with spontaneous recovery) (p = NS). Complications occurred only for left-sided APs and were independent of the approach (transseptal or retrograde). Relapse of AP conduction was more frequent in the group of patients with a manifest than in those with a concealed AP (12 vs 5%), though not significantly. There were no late complications. CONCLUSIONS: Those patients presenting with a tachyarrhythmia due to a concealed AP, compared to those with a manifest AP, were older and had a longer history of tachyarrhythmia. Atrial fibrillation was more frequent in patients with manifest AP. Atrioventricular reciprocating tachycardia episodes were longer-lasting and caused more hospitalizations and more frequently pre-syncope in the group of patients with a concealed AP. Almost all concealed APs were localized in the left side. The retrograde electrophysiological properties were similar. The results of radiofrequency catheter ablation were comparable in both groups.

E/A ratio before cardiac resynchronization therapy predicts left ventricle reverse remodeling.

AIM: Clinical experience shows that about 2 out of 3 patients with indication to resynchronization therapy (CRT) may have improvements in NYHA class, echocardiographic parameters and survival. However, specific clinical or technical parameters that identify responder patients have not yet been found. Aim of the present study was to assess the efficacy of CRT and to estimate the predictive value of specific echocardiographic parameters. METHODS: All patients who underwent CRT from January 2004 till June 2009, at our Institution, were clinically examined and evaluated by echo and ECG before implant. Between January and February 2010, among a population of 55 patients (41 M, 14F, mean age 66.3±5.9), 42 patients (33 M) were considered in the final multiparametric analysis. Of the 13 excluded patients, 6 died, 2 underwent cardiac transplantation and 5 were lost to follow-up. Basal characteristics of the study population were: ischemic etiology in 15 out of 42 patients, back-up defibrillation in 39 patients. The mean follow-up period was 26.2±13.0 months. Patients had been classified as CRT responders if they showed an inverse left ventricle (LV) remodeling, defined as a 10% reduction of end-diastolic diameter (LVEDD) compared to the basal measure. RESULTS: Echo parameters significantly improved after CRT: LVEDD was significantly (P<0.05) reduced (basal vs. CRT: 76±7 mm vs. 64±10 mm, P=0.00004); basal ejection fraction (EF) was 21±5% vs. 37±14% after CRT (P=0.00001); mitral regurgitation (MR) (grading from 1 to 4) was 2.8±0.6 vs. 2.3±0.9 (P=0.00998); QRS duration was 157±25 ms vs. 135±23 ms (P=0.00036), and NYHA class 2.6±0.5 vs. 2.1±0.4, P=0.00006). Only a positive trend of the E/A ratio was observed (P=0.088). Among 42 patients, 24 (57%) had an inverse LV remodeling and were defined as CRT responders. By comparing responder with no-responder patients, the basal values of echo parameters like EF, LVEDD, MR, QRS, NYHA class were similar in the two groups; while E/A was statistically different between the two groups (P=0.02), being less severe in responder patients. CONCLUSION: Our experience confirms that about 2 out of 3 patients are responder to CRT and their clinical improvements remain stable in a long term follow-up. Patients with a less severe E/A ratio are more likely to improve their clinical condition as shown by the reverse remodeling measured through the LVEDD.

Ablation of typical atrial flutter: a prospective study of cooled-tip versus 8-mm-tip catheters.

AIM: Both ablation catheters with irrigated system and 8mm tip-catheters have shown to be more effective for typical atrial flutter radiofrequency (RF) ablation when compared to conventional 4 mm tip catheter. The purpose of this prospective study was to compare the efficiency of radiofrequency catheter ablation (RFA) of the cavotricuspid isthmus using a new type of open irrigation-tip catheter versus 8 mm tip-catheters to eliminate atrial flutter (AFL). METHODS: Sixty consecutive patients, matched for age, presence of cardiopathy, atrial dimensions and comorbidity, underwent RF ablation of cavotricuspid isthmus (CTI) for the treatment of typical atrial flutter, using an open irrigated tip catheter - Surround Flow™ - (N.=30) or an 8-mm-tip catheter (N.=30). The RF pulses were applied point-by-point for 30 seconds, with power limited at 35 w for the irrigated catheter and by temperature control (60/70 w) for the 8-mm catheter. RESULTS: The CTI block was successfully performed in 100% of cases. There was no significant difference with regard to ablation parameters, such as total time of RF ablation (608±324 vs. 556±244 s, P=0.79), number of RF applications (12±8 vs. 10±5, P=0.56), total procedure duration (86.4±23.6 vs. 78.1±22.5 min, P=0.58) and time of fluoroscopy (12±6 vs. 14±6 min, P=0.25) and periprocedural complications (1 groin hematoma in the 8 mm group). During follow-up of 11.6 months on average, one patient in the 8 mm group had recurrence of typical atrial flutter. CONCLUSION: Efficacy and safety of CTI ablation was comparable between both techniques (open irrigated catheter and 8mm tip catheter). The ablation parameters were comparable and homogeneous between the two groups.

Radiofrequency catheter ablation and modulation of atrioventricular conduction in patients with atrial fibrillation.

We attempted radiofrequency ablation of the AV junction with a sequential right- and left-sided approach in 78 patients affected by severely symptomatic, drug refractory atrial fibrillation. Stable third-degree AV block was obtained in 99% of cases and, after 3 months, persisted in 92% of cases. Single session, stepwise, radiofrequency modulation of the AV node was attempted in 13 patients with paroxysmal atrial fibrillation. During sinus rhythm, ablation of the slow and fast AV node pathways was performed in order to increase the nodal refractory period or to slow conduction. Clinically successful modulation of AV conduction was achieved in 15% of cases and persisted during a 3-month follow-up. In conclusion, AV junction ablation is a well-established means of treating atrial fibrillation, but implies the implant of a permanent pacemaker. AV node modulation avoids the pacemaker implant, but is efficacious only in a minority of patients. Thus, in patients affected by paroxysmal atrial fibrillation, AV modulation should be attempted first; if this is ineffective, AV ablation can be performed during the same session.

[Progression to 2d and 3d grade atrioventricular block in patients after electrostimulation for bundle-branch block and syncope: a long-term study]. / La progressione a blocco atrioventricolare di II e III grado nei pazienti elettrostimolati per blocco di branca e sincope: uno studio a lungo termine.

BACKGROUND: Patients with bundle branch block and syncope, especially those with abnormal electrophysiologic study, are at high risk of progression to second-or third-degree atrioventricular block and therefore they often receive a permanent back-up pacemaker. The aim of this study was to evaluate of the incidence of bundle branch block progression to second or third-degree atrioventricular block during long-term follow-up. METHODS: A retrospective study was performed on 60 patients (49 males, age 77 +/- 9 years) with bundle branch block and permanent back-up pacemaker. The patients were subdivided into 3 groups: 13 patients, at pre-implant electrophysiologic study had HV interval > or = 100 msec and/or second- or third-degree atrioventricular block induced by ajmaline i.v. administration (Group 1); 20 patients with HV interval of 70-100 msec and/or HV > or = 120 msec after ajmaline administration (Group 2); 27 patients who had received a permanent pacemaker because of carotid sinus syndrome or sick sinus syndrome (22 patients) or because of recurrent syncopes and negative electrophysiologic study (5 patients) (Group 3). RESULTS: During a mean follow-up of 62 +/- 41 months, 17/60 patients (28%) had progression to second- (n = 4) or third-degree (n = 13) atrioventricular block: atrioventricular block occurred in 54% of Group 1 patients in 25% of Group 2 patients and in 19% of Group 3 patients. The actuarial rate of progression to atrioventricular block for the overall population was, at 5 and 10 years, 25% and 58% respectively; in Group 1 it was 46% and 62%; in Group 2 it was 22% and 55% and in Group 3 it was 21% and 59% (p = 0.06). The patients with right bundle branch block and left anterior hemiblock were at higher risk of progression to atrioventricular block than those with right bundle branch block or left bundle branch block (risk 42% vs 14%, p = 0.06). The presence of an abnormal electrophysiologic study did not increase the progression rate either in the patients with right bundle branch block and left anterior hemiblock (risk of 43%), nor did it in those patients with other types of bundle branch block (risk of 18%). Moreover, the induction of second- or third-degree atrioventricular block during ajmaline administration was associated with a higher risk of block during the follow-up (60% vs 25%, p = 0.06). CONCLUSIONS: Patients treated with pacemaker because of symptomatic bundle branch block have a high risk of progression to second- or third-degree atrioventricular block in the long-term follow-up. The results argue against the practical usefulness of electrophysiological study since a risk stratification could be obtained by the simpler surface electrocardiogram; moreover, risk of block was also present in the patients affected by carotid sinus syndrome or sick sinus syndrome, and in those affected by unexplained syncope with negative electrophysiologic study.