Effects of closed-loop stimulation vs. DDD pacing on haemodynamic variations and occurrence of syncope induced by head-up tilt test in older patients with refractory cardioinhibitory vasovagal syncope: the Tilt test-Induced REsponse in Closed-loop Stimulation multicentre, prospective, single blind, randomized study.

Aims: Closed-loop stimulation (CLS) seemed promising in preventing the recurrence of vasovagal syncope (VVS) in patients with a cardioinhibitory response to head-up tilt test (HUTT) compared with conventional pacing. We hypothesized that the better results of this algorithm are due to its quick reaction in high-rate pacing delivered in the early phase of vasovagal reflex, which increase the cardiac output and the blood pressure preventing loss of consciousness. Methods and results: This prospective, randomized, single-blind, multicentre study was designed as an intra-patient comparison and enrolled 30 patients (age 62.2 ± 13.5 years, males 60.0%) with cardioinhibitory VVS, carrying a dual-chamber pacemaker incorporating CLS algorithm. Two HUTTs were performed one week apart: one during DDD-CLS 60-130/min pacing and the other during DDD 60/min pacing; patients were randomly and blindly assigned to two groups: in one the first HUTT was performed in DDD-CLS (n = 15), in the other in DDD (n = 15). Occurrence of syncope and haemodynamic variations induced by HUTT was recorded during the tests. Compared with DDD, DDD-CLS significantly reduced the occurrence of syncope induced by HUTT (30.0% vs. 76.7%; P < 0.001). In the patients who had syncope in both DDD and DDD-CLS mode, DDD-CLS significantly delayed the onset of syncope during HUTT (from 20.8 ± 3.9 to 24.8 ± 0.9 min; P = 0.032). The maximum fall in systolic blood pressure recorded during HUTT was significantly lower in DDD-CLS compared with DDD (43.2 ± 30.3 vs. 65.1 ± 25.8 mmHg; P = 0.004). Conclusion: In patients with cardioinhibitory VVS, CLS reduces the occurrence of syncope induced by HUTT, compared with DDD pacing. When CLS is not able to abort the vasovagal reflex, it seems to delay the onset of syncope.

Persistence of ICD indication at the time of replacement in patients with initial implant for primary prevention indication: Effect on subsequent ICD therapies.

BACKGROUND: Indication to implantable cardioverter defibrillator (ICD) for primary prevention of sudden death relies on left ventricular ejection fraction (LVEF). We measured the proportion of patients in whom indication to ICD persisted at the time of generator replacement (GR) and searched for predictors of appropriate therapies after GR. METHODS: We identified all consecutive patients who had received an ICD at our hospital, for LVEF ≤35% and no previous arrhythmias or unexplained syncope. Then, we included the 166 patients who outlived their first device and underwent GR. RESULTS: At the time of GR (mean follow-up 59 ± 20 months), ICD indication (i.e. LVEF ≤35% or previously treated ventricular arrhythmias) persisted in 114 (69%) patients. After GR, appropriate ICD therapies were delivered in 30 (26%) patients with persistent ICD indication and in 12 (23%) of the remaining patients (p = 0.656). Nonetheless, the annual rate of therapies was higher in the first group (1.08 versus 0.53 events/year; p < 0.001), as well as the rate of inappropriate therapies (0.03 versus 0 events/year; p = 0.031). The only independent predictor of appropriate ICD therapies after GR was the rate of shocks received before replacement (Hazard Ratio: 1.41; 95% confidence interval: 1.01-1.96; p = 0.041). CONCLUSION: In heart failure with reduced LVEF, ICD indication persisted at the time of GR in 69% of patients. However, even in the absence of persistent ICD indication at GR, the risk of recurrence of arrhythmic events was not null.

Etiological diagnosis, prognostic significance and role of electrophysiological study in patients with Brugada ECG and syncope.

BACKGROUND: Syncope is considered a risk factor for life-threatening arrhythmias in Brugada patients. Distinguishing a benign syncope from one due to ventricular arrhythmias is often difficult, unless an ECG is recorded during the episode. Aim of the study was to analyze the characteristics of syncopal episodes in a large population of Brugada patients and evaluate the role of electrophysiological study (EPS) and the prognosis in the different subgroups. METHODS AND RESULTS: One hundred ninety-five Brugada patients with history of syncope were considered. Syncope were classified as neurally mediated (group 1, 61%) or unexplained (group 2, 39%) on the basis of personal and family history, clinical features, triggers, situations, associated signs, concomitant therapy. Most patients underwent EPS; they received ICD or implantable loop-recorder on the basis of the result of investigations and physician's judgment. At 62±45months of mean follow-up, group 1 showed a significantly lower incidence of arrhythmic events (2%) as compared to group 2 (9%, p<0.001). Group 2 patients with positive EPS showed the highest risk of arrhythmic events (27%). No ventricular events occurred in subjects with negative EPS. CONCLUSION: Etiological definition of syncope in Brugada patients is important, as it allows identifying two groups with different outcome. Patients with unexplained syncope and ventricular fibrillation induced at EPS have the highest risk of arrhythmic events. Patients presenting with neurally mediated syncope showed a prognosis similar to that of the asymptomatic and the role of EPS in this group is unproven.

An anomalous case of acute coronary syndrome: the unexpected autoimmune duo.

: Acute coronary syndrome represents one of the most common causes of admittance to emergency rooms in Western countries. Despite being in the majority of cases the mirror of coronary atherosclerosis, more rare causes could be hidden beyond this presentation, whose identification is often crucial for patients' outcome. We hereby present the case of a 44-year-old woman, with a history of relapsing-remitting multiple sclerosis in treatment with natalizumab, who was admitted to our division for an acute coronary syndrome. At arrival, anaemia and severe thrombocytopenia were observed; thus, no antiplatelet agent was administered. Within a few hours, aphasia occurred. Clinical presentation and the identification of schistocytes at blood smear led to the suspicion of thrombotic thrombocytopenic purpura, which was then confirmed by laboratory analysis. Immediate high-dose steroids and plasma exchange allowed discharging of the patient within a few days without neurological or cardiac sequelae.

Right ventricular septal pacing: Safety and efficacy in a long term follow up.

AIM: To evaluate the safety and efficacy of the permanent high interventricular septal pacing in a long term follow up, as alternative to right ventricular apical pacing. METHODS: We retrospectively evaluated: (1) 244 patients (74 ± 8 years; 169 men, 75 women) implanted with a single (132 pts) or dual chamber (112 pts) pacemaker (PM) with ventricular screw-in lead placed at the right ventricular high septal parahisian site (SEPTAL pacing); (2) 22 patients with permanent pacemaker and low percentage of pacing (< 20%) (NO pacing); (3) 33 patients with high percentage (> 80%) right ventricular apical pacing (RVA). All patients had a narrow spontaneous QRS (101 ± 14 ms). We evaluated New York Heart Association (NYHA) class, quality of life (QoL), 6 min walking test (6MWT) and left ventricular function (end-diastolic volume, LV-EDV; end-systolic volume, LV-ESV; ejection fraction, LV-EF) with 2D-echocardiography. RESULTS: Pacing parameters were stable during follow up (21 mo/patient). In SEPTAL pacing group we observed an improvement in NYHA class, QoL score and 6MWT. While LV-EDV didn't significantly increase (104 ± 40 mL vs 100 ± 37 mL; P = 0.35), LV-ESV slightly increased (55 ± 31 mL vs 49 ± 27 mL; P = 0.05) and LV-EF slightly decreased (49% ± 11% vs 53% ± 11%; P = 0.001) but never falling < 45%. In the RVA pacing control group we observed a worsening of NYHA class and an important reduction of LV-EF (from 56% ± 6% to 43% ± 9%, P < 0.0001). CONCLUSION: Right ventricular permanent high septal pacing is safe and effective in a long term follow up evaluation; it could be a good alternative to the conventional RVA pacing in order to avoid its deleterious effects.

Prevalence of ventricular arrhythmias in patients with cardiac resynchronization therapy without back-up ICD: a single-center experience.

AIMS: Current guidelines recommend cardiac resynchronization therapy (CRT) in selected heart failure patients, but do not precisely clarify when a back-up implantable cardioverter defibrillator (ICD) should be associated (CRT-D). In this study we evaluate the occurrence of ventricular arrhythmias in a population of patients implanted with biventricular pacemaker without a back-up ICD (CRT-P). METHODS: We performed a retrospective analysis on 84 patients (55 men, mean age 74 ±â€Š7 years), implanted with a CRT-P since April 2000. Patients had in 31% an underlying coronary artery disease, in 56% an idiopatic dilated cardiomyopathy and in 13% a valvular disease. An upgrade to CRT-P was performed from previous conventional pacemakers in 36% of cases. Baseline New York Heart Association (NYHA) functional class was II in 25%, III in 63% and IV in 12%. Mean left ventricular ejection fraction was 29.8 ±â€Š8.8% with two-dimensional echo. During follow-up, occurrence of ventricular arrhythmias was assessed clinically and through the pacemaker stored data at the scheduled check-up. RESULTS: During a mean follow-up of 29 months (range 2-127 months), telemetry interrogation revealed unsustained ventricular tachyarrhythmias in 11 of 84 patients (13.1%). Only one patient experienced an episode of sustained ventricular tachycardia. An upgrading to a CRT-D was performed in two patients; one of these patients died suddenly 15 months after the upgrade. Death occurred in 20 of 84 patients (23.8%): 15 for refractory heart failure and five for noncardiac causes. CONCLUSION: Our data show that CRT-P may be well tolerated in selected patients even during a long-term follow-up; and that an upgrade to CRT-D may not be enough to prevent sudden death.

Analysis of electrical and mechanical left atrial properties in patients with persistent atrial fibrillation.

The study of left atrial (LA) mechanical function during atrial fibrillation (AFib) can provide valuable information, particularly if such profiling is related to the cavity electrical substrate and conveys prognostic information. To assess if there is any relation between LA mechanical and electrical asynchrony and if such evaluation can be of interest in stratifying AFib patients. 50 patients with persistent AFib who underwent electrical cardioversion (CV) were evaluated with pre-CV atrial electrograms (AEGs). Electrical asynchrony was classified according to Wells' patterns of AEGs, ranging from most organized (I) to most dispersed (III) one. LA mechanical asynchrony was addressed by transthoracic 2D-speckle-tracking echo and quantified according to time-to-peak standard deviation (TP-SD) of wall strains and their peak values (PS) before CV, after 24 h, at 1 month. Pre-CV a linear, inverse relation between TP-SD and PS (p < 0.001) and a direct linear relation between TP-SD and Wells' classes (p = 0.04) were observed. With sinus rhythm TP-SD decreased (p = 0.023) and PS increased (p < 0.001), suggesting improved LA mechanical milieu. A multivariate analysis, testing the effects of baseline variables in predicting post-CV recurrence of AFib, revealed that amount of TP-SD variation pre/24 h post-CV was the only independent predictor at 6 months (p = 0.046). Speckle tracking-derived LA parameters can describe LA wall forces during AFib, categorizing the asynchronous mechanistic profile of AFib that correlates with the degree of the dispersed LA electrical activity. The amount of changes in LA mechanical asynchrony pre/post-CV seems to have prognostic relevance in predicting SR maintenance.

Transient hyperkalemia-induced T-wave oversensing as a cause of inappropriate ICD discharges.

The present case describes a patient with an implantable cardioverter-defibrillator (ICD) who reported several ICD inappropriate discharges due to transient T-wave oversensing in the setting of acute hyperkalemia. T-wave oversensing was detected only at telemetry interrogation while T-wave amplitude at surface 12-lead electrocardiogram was normal. Oversensing was abolished by reducing potassium levels and by device reprogramming. This case report underscores the importance of identifying a potentially reversible cause of ICD inappropriate discharges and the utility of careful review of stored electrograms. .

Stable ventricular fibrillation in a heterotopic heart transplant recipient.

We present an unusual case of ventricular fibrillation in a conscious patient symptomatic for chest pain and shortness of breath. Almost 20 years ago he underwent heterotopic cardiac transplantation for the treatment of severe idiopathic cardiomyopathy. In the precyclosporine era, this technique was extremely useful because of the high rate of graft rejection in which the maintenance of the native heart could prevent patient death. To date, with the improvements in immunosuppressive therapy, it is generally reserved to a specific subset of conditions. A coronary angiography and a cardiac MRI confirmed the diagnosis. Six months follow-up ECG was unchanged suggesting the persistence of a double heart rhythm in the same body.

Ventricular fibrillation as primary presentation of takotsubo cardiomyopathy after complicated cesarean delivery.

Takotsubo cardiomyopathy typically affects post-menopausal women under severe psychological or physical stress; it also has been reported to develop after medical procedures or surgery. We herein report the rare case of a 30-year-old woman who presented with an episode of ventricular fibrillation after a very complicated cesarean delivery and was successfully resuscitated. Subsequent electrocardiography and echocardiography showed a typical Takotsubo pattern. Within 3 wk, left ventricular systolic function returned to normal.

Long-term follow-up of DDDR closed-loop cardiac pacing for the prevention of recurrent vasovagal syncope.

AIMS: Vasovagal syncope (VVS) is a common disorder characterized by a drop in blood pressure accompanied with bradycardia; although it is generally considered a benign condition, some patients may be highly symptomatic despite general counselling and/or pharmacological therapy. Closed-loop stimulation (CLS), responding to myocardial contraction dynamics, demonstrated effectiveness in short-term prevention of recurrent VVS. The aim of this study was to evaluate CLS pacing in a long-term follow-up. METHODS: The study involved 35 patients (mean age 59 ±â€Š15 years) with 3 years' follow-up (mean 61 ±â€Š35 months). We compared syncopal events and presyncopes before and after CLS implantation. Mean number of syncopes for patients was six (range 1-24; 212 syncopal spells registered) before pacemaker implantation. RESULTS: At follow-up, 29 of 35 patients (83%) were asymptomatic; one patient experienced recurrent loss of consciousness but reported an improvement in the quality of life (one syncope or presyncope per month after CLS, vs. one syncope per week and daily presyncopes before CLS). Five patients experienced syncopal recurrences after CLS (range: 1-7, with a total of 15 episodes); in all the cases, the number of post-CLS syncopes was significantly lower. CONCLUSION: Our study seems to confirm previous results of short-term trials: DDDR-CLS pacing is an extremely useful tool in the prevention of recurring VVS, even in long-term follow-up.

Baseline asynchrony, assessed circumferentially using temporal uniformity of strain, besides coincidence between site of latest mechanical activation and presumed left ventricular lead position, predicts favourable prognosis after resynchronization therapy.

Traditional indexes of LV dyssynchrony (DYS) in pts to be resynchronized are sensitive to noise, while the concordance between LV lead position and site of latest mechanical activation is suggested to be, in these patients, clinically relevant. Both aspects, asynchrony and lead position have been addressed separately but unclear is their potential synergistic role in the clinical evolution of CRT patients. We assessed clinical and echocardiographic outcome, as well as mid-term prognosis, in a population of CHF patients submitted to CRT, stratified according to a novel asynchrony quantitation (temporal uniformity of strain: TUS) method and concordance or not between presumed LV lead position and site of latest mechanical activation. TUS was computed in 85 pts (QRS > 120 ms, EF < 0.35) in whom we measured circumferential and longitudinal strains using speckle-tracking 2D-echocardiography before and 3-6 months after CRT, together with triplane apical LV volumes. Optimal LV lead position in short axis view was defined as concordance of the segment with latest systolic circumferential strain prior-CRT and segment with assumed LV lead position. Assumed LV lead position was defined from a chest X-ray obtained 1 day after implantation and scored as anterior, lateral, posterior or inferior using 2 orthogonal views (antero-posterior and lateral). Following CRT, LV volume decreased (diastolic -8 ± 20%) and EF improved (+6 ± 9%, P < 0.001 for both). Two-way ANOVA revealed TUS improvement post-CRT (+22 ± 68%, P = 0.025), with a clear evidence for more marked asynchrony detectable at circumferential (from 0.53 ± 0.20 to 0.55 ± 0.19) as compared with longitudinal level (from 0.56 ± 0.14 to 0.62 ± 0.14) (P = 0.017). Multivariate analysis revealed that greater baseline asynchrony, as assessed circumferentially (P = 0.079), together with concordance between LV lead position and site of activation (P = 0.012), besides younger age (P = 0.051), longer QRS duration (P = 0.021) and higher baseline EF (P = 0.04),), but not longitudinal TUS (P = 0.231) did predict death from any cause or new episodes of pulmonary or systemic congestion requiring i.v. diuretics during a 529 ± 357 days clinical follow-up. We conclude that DYS indexed by circumferential TUS yields CRT benefits, supporting the idea of targeting TUS-measured DYS as the informative asynchrony quantitative measurement in CRT pts. Significant predictability in medium-term clinical follow-up of patients to be resynchronized is also associated with concordance between site of latest mechanical activation and presumed LV lead position in the present study.

Ventricular fusion mimicking acute inferior myocardial infarction in a patient with a dual-chamber pacemaker.

BACKGROUND AND PURPOSE: Early diagnosis of acute myocardial infarction is based on 12-lead electrocardiography (ECG), however this interpretation could be difficult in patients with ventricular-paced rhythm. SUBJECT: We describe the clinical case of a 44-year-old man already implanted with a dual-chamber closed loop stimulation (CLS) pacemaker (PM) and admitted to our department with an ECG showing ST elevation in the inferior leads. All examinations were negative and showed no abnormalities. After CLS-PM was reprogrammed in order to allow the appearance of spontaneous atrioventricular conduction, we found a complete normalization of ST segment. CONCLUSION: After a careful analysis of admission ECG, ST elevation was interpreted as ventricular fusion due to the presence of a ventricular pacing artifact and the QRS complex being a hybrid of spontaneous and totally paced beats. Intermittent ST elevation, evident only during ventricular fusion should suggest secondary ventricular repolarization and not myocardial injury.

Usefulness of hemodynamic sensors for physiologic cardiac pacing in heart failure patients.

The rate adaptive sensors applied to cardiac pacing should respond as promptly as the normal sinus node with an highly specific and sensitive detection of the need of increasing heart rate. Sensors operating alone may not provide optimal heart responsiveness: central venous pH sensing, variations in the oxygen content of mixed venous blood, QT interval, breathing rate and pulmonary minute ventilation monitored by thoracic impedance variations, activity sensors. Using sensors that have different attributes but that work in a complementary manners offers distinct advantages. However, complicated sensors interactions may occur. Hemodynamic sensors detect changes in the hemodynamic performances of the heart, which partially depends on the autonomic nervous system-induced inotropic regulation of myocardial fibers. Specific hemodynamic sensors have been designed to measure different expression of the cardiac contraction strength: Peak Endocardial Acceleration (PEA), Closed Loop Stimulation (CLS) and TransValvular Impedance (TVI), guided by intraventricular impedance variations. Rate-responsive pacing is just one of the potential applications of hemodynamic sensors in implantable pacemakers. Other issues discussed in the paper include: hemodynamic monitoring for the optimal programmation and follow up of patients with cardiac resynchronization therapy; hemodynamic deterioration impact of tachyarrhythmias; hemodynamic upper rate limit control; monitoring and prevention of vasovagal malignant syncopes.

Diagnosis, management, and outcomes of patients with syncope and bundle branch block.

AIMS: Although patients with syncope and bundle branch block (BBB) are at high risk of developing atrio-ventricular block, syncope may be due to other aetiologies. We performed a prospective, observational study of the clinical outcomes of patients with syncope and BBB following a systematic diagnostic approach. METHODS AND RESULTS: Patients with ≥1 syncope in the last 6 months, with QRS duration ≥120 ms, were prospectively studied following a three-phase diagnostic strategy: Phase I, initial evaluation; Phase II, electrophysiological study (EPS); and Phase III, insertion of an implantable loop recorder (ILR). Overall, 323 patients (left ventricular ejection fraction 56 ± 12%) were studied. The aetiological diagnosis was established in 267 (82.7%) patients (102 at initial evaluation, 113 upon EPS, and 52 upon ILR) with the following aetiologies: bradyarrhythmia (202), carotid sinus syndrome (20), ventricular tachycardia (18), neurally mediated (9), orthostatic hypotension (4), drug-induced (3), secondary to cardiopulmonary disease (2), supraventricular tachycardia (1), bradycardia-tachycardia (1), and non-arrhythmic (7). A pacemaker was implanted in 220 (68.1%), an implantable cardioverter defibrillator in 19 (5.8%), and radiofrequency catheter ablation was performed in 3 patients. Twenty patients (6%) had died at an average follow-up of 19.2 ± 8.2 months. CONCLUSION: In patients with syncope, BBB, and mean left ventricular ejection fraction of 56 ± 12%, a systematic diagnostic approach achieves a high rate of aetiological diagnosis and allows to select specific treatment.

Future easy and physiological cardiac pacing.

The right atrial appendage (RAA) and right ventricular apex (RVA) have been widely considered as conventional sites for typical dual-chamber atrio-ventricular cardiac (DDD) pacing. Unfortunately conventional RAA pacing seems not to be able to prevent atrial fibrillation in DDD pacing for tachycardia-bradycardia syndrome, and the presence of a left bundle branch type of activation induced by RVA pacing can have negative effects. A new technology with active screw-in leads permits a more physiological atrial and right ventricular pacing. In this review, we highlight the positive effects of pacing of these new and easily selected sites. The septal atrial lead permits a shorter and more homogeneous atrial activation, allowing better prevention of paroxysmal atrial fibrillation. The para-Hisian pacing can be achieved in a simpler and more reliable way with respect to biventricular pacing and direct Hisian pacing. We await larger trials to consider this "easy and physiological pacing" as a first approach in patients who need a high frequency of pacing.

Inappropriate asystole detection in early postoperative phase after loop recorder implantation.

The implantable loop recorder is a useful diagnostic tool for patients with unexplained syncope. The capability to automatically detect and store arrhythmic events, implemented in the last generations of these devices, can further improve the diagnostic yield, but this feature can be compromised by inappropriate detection of false arrhythmias. We herein report the case of a patient in which several inappropriate activations of long-lasting asystole occurred in the two days following the implant, probably because of an intermittently loose contact between the device and subcutaneous tissue for a small pocket haematoma.

Do electrical parameters of the cardiac cycle reflect the corresponding mechanical intervals as the heart rate changes?

AIMS: The evoked QT interval can be detected beat by beat through an implanted pacing system. The correlation between the right ventricular paced QT interval and the left ventricular systolic interval is not known. The aim of our study was to collect data on the correlation between QT and systolic and diastolic indexes at different heart rates in patients with dual-chamber rate-responsive pacemakers. METHOD AND RESULTS: The study involved 13 patients [67 +/- 9 years; ejection fraction (EF) 52 +/- 10%] with standard indication for dual-chamber pacing. Patients were evaluated at rest in the supine position. The AV delay was set at 130 ms, and the pacing rate was increased from 90 to 130 bpm (10 bpm steps for 3 min). At the end of each 3 min step, QT intervals were automatically evaluated in real time by means of pacemaker telemetry. We also evaluated heart performance by means of echo-2D (end-diastolic/end-systolic volumes, EF) and echo-Doppler measurements [left ventricular ejection time (LVET) and diastolic filling time (LVDFT), aortic velocity time integral, and systolic volume] and systemic arterial pressure. The QT interval progressively decreased from 330 +/- 20 to 280 +/- 10 ms as the pacing rate was increased from 90 to 130 bpm. The correlation between the QT interval and LVET as a function of the pacing rate was R(2) = 0.966, indicating a good and relatively parallel trend in these two parameters. The correlation between RR-QT (reflecting electrical diastole) and LVDFT (reflecting mechanical diastole) was R(2) = 0.975. The index LVET/QT (ratio between mechanical and electrical systole) was constant in the range 90-120 bpm, but significantly decreased at 130 bpm: the mechanical LVET shortens more than the electrical QT does at the highest heart rates. CONCLUSION: In paced patients at rest and during artificially increased heart rates, QT interval dynamics is closely correlated with changes in ejection time, thus constituting an electrical parameter of systolic time. A similar correlation exists between RR-QT, as a diastolic electrical interval, and the DFT.

Left ventricular torsion in paced patients.

BACKGROUND: In healthy people the left ventricle presents a counter-clockwise apical rotation and a clockwise basal rotation ending in late systole. In early systole (during isovolumic contraction) there is a fast and inverse rotation (counter-clockwise at the base and clockwise at the apex). This opposite rotation between apex and base produces the systolic torsion of the left ventricle. The effect of permanent conventional pacing on this torsion is little known. OBJECTIVES: The aim of this study was to assess, by speckle tracking echocardiography, left ventricular rotation and torsion in patients conventionally paced at the apex of the right ventricle. METHODS: Left ventricular apical and basal rotation and the consequent torsion were evaluated by means of speckle tracking echocardiography, in 13 paced patients, without ischemic or valvular disease, and in 17 healthy participants. Left ventricular dyssynchrony was evaluated by means of temporal uniformity of strain. RESULTS: In the paced group there was a significant reduction in early-systolic clockwise torsion (-0.4 degrees +/- 1.2 vs. -1.5 degrees +/- 1.6; P = 0.04), and in late-systolic counter-clockwise torsion (15.1 degrees +/- 4.3 vs. 19.1 degrees +/- 5.5; P = 0.03). Circumferential temporal uniformity of strain averaged significantly lower in paced patients. CONCLUSIONS: Conventional pacing from the apex of the right ventricle alters both the torsional mechanic and the synchrony of the left ventricle.