Restoration of Life Expectancy After Transcatheter Edge-to-Edge Mitral Valve Repair

BACKGROUND

Survival data after mitral transcatheter edge-to-edge repair (TEER) are scarce, and its impact on predicted life expectancy is unknown.

OBJECTIVES

The aim of this study was to estimate the impact of TEER on postprocedural life expectancy among patients enrolled in the MitraSwiss registry through a relative survival (RS) analysis.

METHODS

Consecutive TEER patients 60 to 89 years of age enrolled between 2011 and 2018 (N = 1140) were evaluated. RS was defined as the ratio between post-TEER survival and expected survival in an age-, sex- and calendar period-matched group derived from the Swiss national 2011 to 2019 mortality tables. The primary aim was to assess 5-year survival and RS after TEER. The secondary aim was to assess RS according to the etiology of mitral regurgitation, age class and sustained procedural success over time.

RESULTS

Overall, 5-year survival after TEER was 59.3% (95% CI: 54.9%-63.4%), whereas RS reached 80.5% (95% CI: 74.6%-86.0%). RS was 91.1% (95% CI: 82.5%-98.6%) in primary mitral regurgitation (PMR) and 71.5% (95% CI: 63.0%-79.3%) in secondary mitral regurgitation (SMR). Patients 80 to 89 years of age (n = 579) showed high 5-year RS (93.0%; 95% CI: 83.3%-101.9%). In this group, restoration of predicted life expectancy was achieved in PMR with a 5-year RS of 100% (95% CI: 87.9%-110.7%), whereas sustained procedural success increased the RS rate to 90.6% (95% CI: 71.3%-107.3%) in SMR.

CONCLUSIONS

Mitral TEER in patients 80 to 89 years of age is able to restore predicted life expectancy in PMR, whereas in SMR with sustained procedural success, high RS estimates were observed. Our analysis suggests that successful, sustained mitral regurgitation reduction is key to survival improvement, particularly in patients 80 to 89 years of age.

[The Old-Age Heart]

The Old-Age Heart Abstract. Knowledge of cardiovascular changes in old age and their therapeutic options is important. Old age can lead to hypertrophy of the left ventricle, diastolic dysfunction, heart valve changes and pulmonary hypertension. Patients often develop arterial hypertension. Valvular changes are common in people over 100 years of age (aortic stenosis and mitral insufficiency). The risk of coronary heart disease is 35 % for men and 24 % for women. In old age, sinus node dysfunction and atrial fibrillation are common. 25 % of all strokes are cardiac embolisms in atrial fibrillation. Cardiac interventions in the elderly are increasingly frequent and include coronary catheter revascularization or valve interventions (percutaneous aortic valve replacement or MitraClip). Optimal therapy in old age includes not only cardiovascular interventions also include drugs and a lifestyle modification and mainly serves to improve the quality of life.

[Catheter based mitral valve repair for severe mitral regurgitation: patient selection]

The catheter-based mitral valve repair is a novel technology for the treatment of severe mitral regurgitation (MR). This technique is suitable for elderly patients with pronounced co-morbidities who are deemed to be high risk for conventional heart surgery. A meaningful reduction of mitral regurgitation leads to improvement of symptoms and quality of life. Studies also demonstrate reverse remodeling of the left ventricle. In heart failure patients with severe MR percutaneous repair reduces re-hospitalization rates>50% in comparison to optimal medical treatment. For degenerative MR conventional surgery is the gold standard, whereas for high surgical risk patients and for severe functional MR percutaneous repair is an alternative.

Clinical Long-Term Response to Cardiac Resynchronization Therapy Is Independent of Persisting Echocardiographic Markers of Dyssynchrony

BACKGROUND

The aim of the study was to prove the concept that correction of established parameters of dyssynchrony is a requirement for favorable long-term outcome in patients with cardiac resynchronization therapy (CRT), whereas patients with persisting dyssynchrony should have a less favorable response.

METHODS

After CRT implantation and optimization of dyssynchrony parameters, we evaluated whether correction or persistence of dyssynchrony predicted long-term outcome. Primary endpoint was a combination of cardiac mortality/heart transplantation and hospitalization due to worsening heart failure, and secondary endpoint was NYHA class.

RESULTS

One hundred twenty-eight consecutive patients (mean age 68 ± 10 years) undergoing CRT with a mean left ventricular ejection fraction of 27±9% were followed for 27 ± 19 months. All cause mortality was 17.2%, cardiac mortality was 7.8% and 3.1% had to undergo heart transplantation. Rehospitalization due to worsening heart failure was observed in 14.8%. NYHA class before CRT implantation was 2.8 ± 0.8 and improved during follow-up to 2.0 ± 0.8 (P < 0.001). A clinical response was observed in 76% (n = 97) and an echocardiographic response was documented in 66% (n = 85). After individually optimized AV and VV intervals with echocardiography, atrioventricular dyssynchrony was still present in 7.2%, interventricular dyssynchrony in 13.3% and intraventricular dyssynchrony in 16.4%. Despite persistent atrioventricular, interventricular and intraventricular dyssynchrony at long-term follow-up, the combined primary and secondary endpoints did not differ compared to the group without mechanical dyssynchrony (P = ns). QRS duration with biventricular stimulation did not differ between responders vs. nonresponders.

CONCLUSION

After successful CRT implantation, clinical long-term response is independent of correction of dyssynchrony measured by echocardiographic parameters and QRS width.

Initial results of linear duty-cycled radiofrequency for atypical flutter and atrial tachycardia

BACKGROUND

Duty-cycled radiofrequency (DCRF) is increasingly used for ablation of atrial fibrillation (AF). Many patients also have atrial flutter (AFL). Recently, a linear multielectrode has been shown to create linear block at the cavotricuspid isthmus and in the left atrium (LA).

OBJECTIVE

To map and ablate atypical AFL and atrial tachycardias (ATs) in the right and LA using a linear multielectrode with DCRF.

METHODS

The linear multielectrode delivers DCRF at 20-45 W maximum in 1:1 unipolar/bipolar temperature-controlled mode. Target temperatures were manually titrated to 60 °C in the LA, if power >5W indicated adequate passive cooling.

RESULTS

A total of 76 AT/AFL were targeted in 57 patients. Acute success was reached in 14/15 (93%) right AT, in 17/22 (77%) left atrial roof AFL, in 5/6 (83%) septal AFL, in 9/9 (100%) other left atrial AT, but only in 8/23 (35%) AFL from the mitral isthmus (which rose to 13/23 [57%] with additional use of irrigated radiofrequency). Nevertheless, freedom of AF/AFL 10 ± 6 months after a single procedure was documented in 92% of right AT, 71% of roof AFL, 73% for mitral AFL, and 60% of septal or other LA AT/AFL. No char formation was noted. However, frequent induction of AF and one case of asystole occurred during delivery of DCRF in a pacemaker patient.

CONCLUSION

The linear multielectrode allows mapping and ablation of atypical AFL/AT. Freedom of AF/AT was reached in 60%-92% depending on localization and number of arrhythmias. Technical modifications will improve safety and efficacy.

Intravenous enoxaparin versus unfractionated heparin in unselected patients undergoing percutaneous coronary interventions: the Zurich enoxaparin versus unfractionated heparin in PCI study (ZEUS)

AIMS

To evaluate the efficacy and safety of intravenous enoxaparin as an alternative to unfractionated heparin (UFH) as antithrombotic therapy in unselected patients undergoing percutaneous coronary intervention (PCI).

METHODS AND RESULTS

Eight hundred and seventy-six (876) consecutive eligible patients undergoing PCI were prospectively randomised to either intravenous enoxaparin 0.75 mg/kg or dose-adjusted UFH in this open-label study that was prematurely stopped due to slow recruitment. Randomisation was stratified on elective PCI or PCI for acute coronary syndrome (ACS). The primary endpoint was a combination of death, myocardial infarction, unplanned target vessel revascularisation and major bleeding at 30 days. Secondary endpoint was a composite of major and minor bleeding and thrombocytopenia < 50x109. The primary endpoint of intravenous enoxaparin did not differ from those of UFH (5.5% vs. 7.0%, p=ns) whereas safety endpoints were reduced with enoxaparin compared to UFH (9.9% vs. 20.0%, p<0.001). Among 229 (26%) patients presenting with ACS, the incidence of both, the primary and secondary endpoints, was lower with enoxaparin as compared to UFH (1.8% vs. 12.9% and 14.2% vs. 31%, p<0.001 and p=0.003, respectively).

CONCLUSIONS

Due to the premature halting of the study and the low event rate, these data are observational only, and no definite conclusion could be made concerning efficacy and safety of intravenous enoxaparin as an alternative to UFH in unselected patients undergoing PCI.

Long-term survival and functional outcome of unselected patients undergoing percutaneous coronary intervention for acute myocardial infarction

BACKGROUND

Percutaneous coronary intervention (PCI) is the most effective reperfusion modality in patients with acute myocardial infarction (MI). Data concerning long-term survival and functional outcome are sparse.

METHODS

One thousand consecutive patients treated by emergency PCI were systematically ana-lysed in a single-centre registry. Multivariate predictors of in-hospital mortality, post-discharge mortality and late functional capacity were identified.

RESULTS

Follow-up was completed for 978 patients. The median clinical follow-up length was 3.2 years. In-hospital and post-discharge mortality were 7.6% and 7.3%, respectively. Annualised post-discharge mortality remained stable over time at 2% per year. Independent predictors of in-hospital death were cardiogenic shock, TIMI flow <3 after PCI, left ventricular ejection fraction <40%, age and time to patent artery >6 h. Independent predictors of post-discharge mortality were TIMI flow after PCI <3, prior MI, elevated glucose levels at admission, and increasing age. In contrast, cardiogenic shock, time to patent artery and left ventricular ejection fraction <40% were not independently associated with post-hospital death. At late follow-up, 47% of patients had normal functional capacity and 49.1% were in New York Heart Association functional class II. Predictors of impaired functional capacity at follow-up were age, gender, smoking habits and multivessel coronary disease.

CONCLUSIONS

Post-discharge mortality after PCI for acute MI was 2% per year. Significant differences exist between predictors of in-hospital and post-discharge mortality. The functional capacity of surviving patients was remarkably good, even when presented in cardiogenic shock.

Atrium-driven Mitral Annulus Motion Velocity Reflects Global Left Ventricular Function and Pulmonary Congestion During Acute Biventricular Pacing

BACKGROUND

The short-term effect of acute biventricular pacing on cardiac function in patients with chronic heart failure undergoing heart surgery is widely unknown. The present study was designed to determine whether mitral annular tissue Doppler imaging (TDI) is useful to predict acute changes in global systolic function determined by the continuous cardiac output method that was measured postoperatively during various pacing configurations in patients with depressed left ventricular (LV) function.

METHODS

TDI peak velocities of systolic (Sm), early diastolic (Em), and late diastolic (Am) mitral annular motion waves were measured in 17 patients (age 67 +/- 8 years, 10 male) with depressed LV systolic function (LV ejection fraction < or = 35%) and QRS duration > 120 ms undergoing temporary epicardial biventricular pacing after aortocoronary bypass and valve surgery. TDI velocities, QRS duration on surface electrocardiogram, cardiac index (CI), right atrial pressure, pulmonary artery pressure, and pulmonary capillary wedge (PCW) pressure were measured simultaneously during various pacing configurations (right atrial-biventricular, right atrial-LV, right atrial-right ventricular, atrial inhibited, and no pacing).

RESULTS

Univariate linear regression analysis showed a good correlation between Am and CI (r = 0.53, P = .0001) determined in all pacing modes, a weak correlation between Sm and CI (r = 0.31, P = .017), and no correlation between Em and CI (r = 0.21, P = .074). Am > 6 cm/s predicted a CI of 2.5 L/min/m(2) or more with a sensitivity of 95% and a specificity of 30%. All TDI values correlated negatively with PCW (r = -0.53, P = .0001 for Sm; r = -0.34, P = .01 for Em; r = -0.50, P = .0001 for Am). Am greater than 6 cm/s predicted a PCW of 16 mm Hg or less with a specificity of 100% and a sensitivity of 34%. Mean values of TDI velocities and hemodynamic parameters were not significantly different between each pacing configuration.

CONCLUSIONS

Peak Am mitral annular velocity correlates well with CI and PCW, respectively, thus providing an easy means to assess LV systolic function and pulmonary congestion during cardiac pacing in chronic heart failure.

Acute biventricular pacing after cardiac surgery has no influence on regional and global left ventricular systolic function

BACKGROUND

Cardiac resynchronization therapy has been shown to improve systolic function in patients with advanced chronic heart failure and electromechanical delay (QRS width > 120 ms). However, the effect of acute biventricular (BiV) pacing on perioperative haemodynamic changes is not well defined. In the present study, acute changes in regional left ventricular (LV) systolic function determined by tissue Doppler imaging (TDI) and global LV systolic function determined by the continuous cardiac output method were measured during various pacing configurations in patients with depressed LV systolic function undergoing heart surgery.

METHODS

Twenty-six patients (age 68 +/- 8 years, 15 males) with depressed systolic LV function (LV ejection fraction <or=35%), symptomatic heart failure, and a QRS duration of > 120 ms undergoing temporary epicardial BiV pacing after aortocoronary bypass and valve surgery were included. QRS duration on surface electrocardiogram (ECG), TDI (systolic velocities of septal and lateral mitral annulus), cardiac index (CI), right atrial pressure, pulmonary artery pressure (PAP), and pulmonary capillary wedge pressure (PCW) were measured during various pacing configurations [no pacing (intrinsic rhythm), right atrial-biventricular (RA-BiV pacing), right atrial-left ventricular (RA-LV), right atrial-right ventricular (RA-RV), and AAI pacing].

RESULTS

There were no differences in QRS duration during intrinsic rhythm, RA-BiV pacing, and AAI pacing. However, RA-LV and RA-RV stimulations showed a longer QRS duration (P < 0.01 vs. intrinsic rhythm, RA-BiV pacing, and AAI, respectively). Tissue Doppler velocities of the septal and lateral mitral annulus were comparable in all pacing modes. Neither CI nor PAP or PCW showed significant differences during the various pacing configurations. There was a positive correlation between regional (TDI) and global (CI) parameters of LV systolic function. Conclusions Biventricular pacing after heart surgery does not improve parameters of regional and global LV systolic function acutely in patients with heart failure and intraventricular conduction delay and, thus, may not reflect changes observed with chronic BiV pacing.

Single-chamber ventricular pacing increases markers of left ventricular dysfunction compared with dual-chamber pacing

AIMS

Large randomized trials comparing DDD with VVI pacing have shown no differences in mortality, but conflicting evidence exists in regard to heart failure endpoints. Here we evaluated the effect of pacing mode on serum levels of brain natriuretic peptide (BNP) and amino-terminal-proBNP (NT-proBNP). Methods Forty-one patients (age 73 +/- 10 years) with dual-chamber pacemakers were included in a prospective, single-blind, randomized crossover study evaluating the impact of DDD(R)/VDD versus VVI(R) mode on objective and functional parameters. Data were collected after a 2-week run-in phase and after 2 weeks each of VVI(R) and DDD(R)/VDD pacing or vice versa. Results BNP and NT-proBNP levels during DDD(R)/VDD stimulation (151 +/- 131 and 547 +/- 598 pg/mL) showed no change compared with baseline (154 +/- 130 and 565 +/- 555 pg/mL), but a significant 2.4-fold increase was observed during VVI(R) mode [360 +/- 221 and 1298 +/- 1032 pg/mL; P < 0.001 compared with DDD(R)/VDD]. The assessment of functional class, the presence of pacemaker syndrome [49% in VVI(R) mode] and the patients' preferred pacing mode showed significant differences in favour of DDD(R)/VDD pacing.

CONCLUSION

Patients can differentiate between DDD(R)/VDD and VVI(R) pacing, and prefer the former. Compared with DDD(R)/VDD pacing, VVI(R) stimulation induces a two- to three-fold increase in serum BNP and NT-proBNP levels.

Diagnostic yield of automatic and patient-triggered ambulatory cardiac event recording in the evaluation of patients with palpitations, dizziness, or syncope

BACKGROUND

Recent studies have shown that patient-triggered cardiac event recorders (CER) have an increased diagnostic yield and are more cost effective than conventional 24-h-Holter electrocardiograms (ECGs) for the evaluation of sporadic, potentially arrhythmia-related symptoms.

HYPOTHESIS

The aim of this study was to determine the diagnostic yield of a patient-triggered CER combined with continuous automatic arrhythmia detection in the evaluation of sporadic dizziness/syncope or palpitations and its clinical relevance in assessing the further management.

METHODS

We investigated 101 consecutive outpatients (54 +/- 20 years, 40 women), referred for evaluation of sporadic dizziness and syncope (36%) or palpitations (64%) of suspected rhythmogenic origin. All were monitored by patient-triggered CER with continuous automatic arrhythmia detection.

RESULTS

After a mean monitoring period of 103 +/- 38 h, 83 patients registered symptoms and 57 patients had diagnostic or therapeutic relevant arrhythmias (relA). A total of 196 episodes of relA were recorded; 31 (16%) episodes were patient-triggered and 165 (84%) automatically recorded. Diagnostic relevant episodes (relA and/or typical symptoms) occurred in 94 patients, in 54% after the first 24 h of monitoring. According to the results of the CER, 80 patients needed no further diagnostic evaluation; 20 had additional diagnostic tests.

CONCLUSIONS

Cardiac event recorders with a continuous automatic arrhythmia detection function are a well-tolerated device for sporadic, potentially arrhythmia-related symptoms. The patient-triggered mode alone is not sufficiently reliable; the automatic continuous arrhythmia detection function has additional diagnostic and therapeutic consequences. In 54% of all patients, the first diagnostic event would not have been recorded with a single conventional 24-h-Holter ECG.

Admission glucose concentrations independently predict early and late mortality in patients with acute myocardial infarction treated by primary or rescue percutaneous coronary intervention

BACKGROUND

In patients with acute myocardial infarction (MI), increased plasma glucose levels at hospital admission are associated with worse outcome. We aimed to assess the predictive value of admission glucose concentrations on short- and long-term mortality in patients with acute MI undergoing primary or rescue percutaneous coronary intervention (PCI).

METHODS

We analyzed the 30-day and long-term (mean follow-up 3.7 years) outcome of 978 patients prospectively included in a single-center registry of patients with acute MI treated with PCI within 24 hours after onset of symptoms. Patients were classified according to plasma glucose levels at admission: < 7.8 mmol/L (group I, n = 322), 7.8 to 11 mmol/L (group II, n = 348), and > 11.0 mmol/L (group III, n = 308).

RESULTS

Mortality at 30 days was 1.2% in group I, 6.3% in group II, and 16.6% in group III (P < .001). After multivariate adjustment for age, the presence of cardiogenic shock, and TIMI 3 flow after PCI, the association of mortality with glucose classification remained significant (P value for trend = .003). The relative risk of death at 30 days for group III versus group I was 3.9 (95% CI 1.2-13.2). During long-term follow-up, mortality was similar in groups I and II. However, in group III adjusted mortality remained significantly increased compared with group I (relative risk 1.76, CI 1.01-3.08).

CONCLUSIONS

In patients undergoing emergency PCI for acute MI, glucose levels at hospital admission are predictive for short- and long-term survival. Knowledge of admission glucose levels may improve initial bedside risk stratification.

Ibutilide in persistent atrial fibrillation refractory to conventional cardioversion methods

BACKGROUND

Electrical cardioversion of atrial fibrillation seems to be enhanced by pretreatment with ibutilide, but only few is known about the effects of ibutilide in atrial fibrillation which failed to convert with class III antiarrhythmic agents and electrical cardioversion. The objectives of this study were to evaluate the efficacy and safety of ibutilide administration in patients with persistent atrial fibrillation refractory to long-term therapy with class III antiarrhythmic drugs and transthoracic cardioversion.

METHODS

Prospective study in 22 patients (16 men and 6 women, mean age 63+/-9 years) with structural heart disease and persistent atrial fibrillation for a mean duration of 39+/-50 (range 1-145) months. All patients had failed to convert to sinus rhythm after transthoracic cardioversion while on treatment with class III antiarrhythmic drugs (amiodarone in 82%, sotalol in 18%). One milligram of ibutilide was administered in all patients and electrical cardioversion was performed again, if necessary.

RESULTS

The total conversion rate to sinus rhythm was 95% (21 of 22 patients). Two patients (9%) were successfully converted after ibutilide alone and 19 patients (86%) when transthoracic cardioversion was repeated after ibutilide. The QTc intervals increased from 451+/-28 to 491+/-49 ms (p<0.001) after ibutilide. No adverse effects occurred. The rate of freedom from atrial fibrillation after 1 month of follow-up was 64%.

CONCLUSIONS

The efficacy of concomitant use of ibutilide infusion and, if necessary, repeated transthoracic cardioversion for restoration of sinus rhythm in long-term persistent atrial fibrillation and previously failed antiarrhythmic and electrical cardioversion was 95%. There were no adverse effects associated with ibutilde administration. Our results suggest that this combined strategy may be safe and successful in patients with atrial fibrillation resistant to conventional cardioversion methods and may be an alternative to internal cardioversion.

Risks and benefits of optimised medical and revascularisation therapy in elderly patients with angina ? on-treatment analysis of the TIME trial

AIM

To assess treatment effects of optimised medical therapy and PCI or CABG surgery on one-year outcome in patients 75 years old with chronic angina.

METHODS AND RESULTS

On-treatment analysis of the TIME data: all re-vascularised patients (REVASC n=174: 112 randomised to revascularisation and 62 to drugs with late revascularisation) were compared to all patients on continued drug therapy (MED n=127: 86 randomised to drugs and 41 to revascularisation only). Baseline characteristics of both groups were similar (age 80 +/- 4 years). Risk of death at one year (adjusted hazard ratio (HR)=1.31; 95%-CI: 0.58-2.99; P=0.52) and of death/infarction (adjusted hazard RATIO=1.77; 95%-CI 0.91-3.41; P=0.09) were comparable between REVASC and MED patients. Furthermore, the risk of death within 30 days was even slightly lower among REVASC patients (unadjusted hazard RATIO=0.73; 95%-CI: 0.21-2.53; P=0.98). Overall, REVASC patients had greater improvements in symptoms and well-being than MED patients (P<0.01). Surgical patients had similar mortality rates as angioplasty patients, but they also had greater symptomatic improvements (P<0.01).

CONCLUSION

Treated medically, elderly patients with chronic angina have a similarly high 30-day and one-year mortality as patients of the same age being re-vascularised; however, they can expect lower improvements in symptoms and well being.

Prevention of atrial fibrillation after cardiac valvular surgery by epicardial, biatrial synchronous pacing

OBJECTIVE

Postoperative atrial fibrillation (AF) after cardiac surgery is a frequent complication after valvular surgery (30-60%). The purpose of this prospective, randomized study was to determine if biatrial synchronous pacing reduces postoperative AF after cardiac valvular surgery as compared to conventional therapy.

METHODS

Eighty patients subjected to valvular surgery (52 men, age 66 +/- 10 years) were randomized to one of two groups: one group was treated with biatrial, synchronous pacing (BAP) for 72 h postoperatively (n=40) the other group received no atrial pacing (controls; n=40). All patients had one pair of epicardial wires attached to the right atrium. An additional electrode was placed to the left atrium in the BAP group. These patients were continuously paced at a rate of 10 beats per minute higher than the intrinsic rate starting immediately after surgery. All patients were monitored with full disclosure telemetry or Holter monitors to identify onset of AF.

RESULTS

Eighteen of the 40 patients in the control group (45%) developed AF within the first 3 days postoperatively as compared to eight patients (20%) in the BAP group (P=0.02). No complications occurred associated with the placement, maintenance and removal of the atrial pacing electrodes.

CONCLUSIONS

Temporary, biatrial synchronous pacing during the first 3 postoperative days is safe and has a significant rhythm-stabilizing effect in patients undergoing valvular cardiac surgery.

Pragmatische Abklärungsstrategie bei Synkope

Die Synkope ist ein unspezifisches Symptom für ein breites Spektrum zugrunde liegender Erkrankungen. Voraussetzung für den sinnvollen Einsatz diagnostischer Mittel sind die Kenntnis der pathophysiologischen Grundlagen und ein strukturiertes, diagnostisches Vorgehen, da Synkopepatienten häufig zahlreichen, teuren Abklärungen unterzogen werden. In knapp der Hälfte der Fälle kann die Ursache der Synkope allein aufgrund von Anamnese, klinischer Untersuchung und Ruhe-EKG gefunden werden. Wichtig für eine effektive und kosteneffiziente, diagnostische Abklärung ist dabei die Zusammenarbeit zwischen Grundversorger, Kardiologe, Neurologe und Psychiater im Sinne der oft propagierten Netzwerkbildung.

Quality of life and exercise capacity in patients with prolonged PQ interval and dual chamber pacemakers: a randomized comparison of permanent ventricular stimulation vs intrinsic AV conduction

AIMS

The aim of this study was to assess quality of life (QoL) and exercise capacity during permanent ventricular stimulation (PVS) compared with intrinsic atrioventricular conduction (IAVC) in patients with dual chamber pacemakers (PMs) and an intrinsic PQ interval >210 ms. Dual chamber PMs in patients with atrioventricular (AV) block are usually programmed to PVS in VDD or DDD mode, although IAVC is preserved, but prolonged. This results in PVS, although long periods of IAVC may occur.

METHODS AND RESULTS

Fourteen consecutive patients (age 76 +/- 6 years; intermittent high degree AV block in six patients, binodal disease in eight patients) were enroled in a prospective, randomized, single blind, crossover study of IAVC vs PVC. To permit IAVC, programmed AV delays were prolonged. At the end of each phase, QoL scores were assessed using a questionnaire and echocardiography and cardiopulmonary stress tests were performed. During the study period with IAVC, 95 +/- 10% of the beats were conducted intrinsically. QoL scores (28.3 +/- 11 vs 29.3 +/- 13; P = 0.68), peak exercise capacity (5.4 +/- 2.4 vs 5.2 +/- 2.9 METs; P = 0.35) and peak oxygen uptake (19.8 +/- 4.5 vs 18.8 +/- 5.2 ml/kg/min; P = 0.16) were comparable during IAVC and PVS, respectively. Similar echocardiographic values were found for left ventricular (LV) ejection fraction (50 +/- 9% vs 51 +/- 10%; P = 0.67) and velocity time integral at the left ventricular outflow tract (24 +/- 5 vs 22 +/- 6 cm; P = 0.20), respectively.

CONCLUSIONS

We conclude that in patients with dual chamber PMs and intermittent high degree AV block neither PVS nor IAVC is superior with respect to QoL or exercise capacity. Therefore, pulse generators may be programmed to IAVC to extend their longevity.

Characteristics of patients with abnormal stress technetium Tc 99m sestamibi SPECT studies without significant coronary artery diameter stenoses

BACKGROUND

Single-photon emission computed tomography (SPECT) sestamibi (MIBI) is an excellent tool for detection of coronary artery disease (CAD), preoperative risk assessment, and follow-up management after coronary revascularization. While the sensitivity of MIBI SPECT for detecting CAD has been reported to exceed 90%, the specificity ranges between 53-100%.

HYPOTHESIS

The study was undertaken to assess characteristics of patients with abnormal stress technetium Tc99m sestamibi SPECT (MIBI) studies without significant coronary artery diameter stenoses (< 50%).

METHODS

Between January 1999 and November 2000, 270 consecutive patients were referred for coronary angiography due to reversible MIBI uptake defects during exercise. In 41 patients (15%; 39% women, mean age 59 +/- 9 years), reversible MIBI uptake defects were assessed although coronary angiography showed no significant CAD. These patients were compared with age- and gender-matched patients with perfusion abnormalities (39% women, mean age 60 +/- 9 years), due to significant CAD (coronary artery stenosis > 50%).

RESULTS

There were no significant differences between the two groups regarding body mass index, left bundle-branch block (LBBB), or method of stress test (dipyridamole in patients with LBBB or physical inactivity [n = 11] and exercise in all the others [n = 30]). Left ventricular hypertrophy (44 vs. 23%, p = 0.05) and left anterior fascicular block (LAFB) (17 vs. 0%, p = 0.005) were more common in patients with perfusion abnormalities with no significant CAD, whereas ST-segment depression during exercise (17 vs. 37% p = 0.05) and angina during exercise (15 vs. 29%, p = 0.02) were significantly less common than in patients with abnormal MIBI perfusion studies and angiographically significant CAD. Sestamibi uptake defects during exercise were significantly smaller in patients without significant CAD than in matched controls with significant CAD (p < 0.0004).

CONCLUSION

Of 270 consecutive patients, 41 (15%) referred to coronary angiography due to reversible MIBI uptake defects showed coronary artery stenoses < 50%. Twenty-six (10%) of these presented angiographically normal coronary arteries. The significantly higher proportion of left ventricular hypertrophy and LAFB in patients with reversible MIBI uptake defects without significant CAD suggest microvascular disease, angiographically underestimated CAD, and conduction abnormalities as underlying mechanisms.

Outcome of elderly patients with chronic symptomatic coronary artery disease with an invasive vs optimized medical treatment strategy: one-year results of the randomized TIME trial

CONTEXT

The risk-benefit ratio of invasive vs medical management of elderly patients with symptomatic chronic coronary artery disease (CAD) is unclear. The Trial of Invasive versus Medical therapy in Elderly patients (TIME) recently showed early benefits in quality of life from invasive therapy in patients aged 75 years or older, although with a certain excess in mortality.

OBJECTIVE

To assess the long-term value of invasive vs medical management of chronic CAD in elderly adults in terms of quality of life and prevention of major adverse cardiac events.

DESIGN

One-year follow-up analysis of TIME, a prospective randomized trial with enrollment between February 1996 and November 2000.

SETTING AND PARTICIPANTS

A total of 282 patients with Canadian Cardiac Society class 2 or higher angina despite treatment with 2 or more anti-anginal drugs who survived for the first 6 months after enrollment in TIME (mean age, 80 years [range, 75-91 years]; 42% women), enrolled at 14 centers in Switzerland.

INTERVENTIONS

Participants were randomly assigned to undergo coronary angiography followed by revascularization (if feasible) (n = 140 surviving 6 months) or to receive optimized medical therapy (n = 142 surviving 6 months).

MAIN OUTCOME MEASURES

Quality of life, assessed by standardized questionnaire; major adverse cardiac events (death, nonfatal myocardial infarction, or hospitalization for acute coronary syndrome) after 1 year.

RESULTS

After 1 year, improvements in angina and quality of life persisted for both therapies compared with baseline, but the early difference favoring invasive therapy disappeared. Among invasive therapy patients, later hospitalization with revascularization was much less likely (10% vs 46%; hazard ratio [HR], 0.19; 95% confidence interval [CI], 0.11-0.32; P<.001). However, 1-year mortality (11.1% for invasive; 8.1% for medical; HR, 1.51; 95% CI, 0.72-3.16; P =.28) and death or nonfatal myocardial infarction rates (17.0% for invasive; 19.6% for medical; HR, 0.90; 95% CI, 0.53-1.53; P =.71) were not significantly different. Overall major adverse cardiac event rates were higher for medical patients after 6 months (49.3% vs 19.0% for invasive; P<.001), a difference which increased to 64.2% vs 25.5% after 12 months (P<.001).

CONCLUSIONS

In contrast with differences in early results, 1-year outcomes in elderly patients with chronic angina are similar with regard to symptoms, quality of life, and death or nonfatal infarction with invasive vs optimized medical strategies based on this intention-to-treat analysis. The invasive approach carries an early intervention risk, while medical management poses an almost 50% chance of later hospitalization and revascularization.

Long-term results after acute percutaneous transluminal coronary angioplasty in acute myocardial infarction and cardiogenic shock

The aim of this study was to determine the long-term outcome in unselected, consecutive patients after acute percutaneous transluminal angioplasty (PTCA) for acute myocardial infarction (AMI) complicated by cardiogenic shock. This involved a follow-up study from a prospectively conducted patient registry in a tertiary referral center. A total of 59 patients (10 female/49 male; median age 62 years (32-91)) with percutaneous transluminal cardiac interventions in primary cardiogenic shock were identified between January 1995 and January 2000. Twenty-two patients (37%) had been resuscitated successfully before intervention. The in-hospital mortality of shock patients was 36% (n=21, median age 68 (47-84)). The median follow-up of survivors was 18.1 (7-57.3) months, during which three further patients died (8%; two because of sudden cardiac deaths, one because of acute reinfarction). Achievement of thrombolysis in myocardial infarction (TIMI) flow III after acute PTCA (84% in survivors vs. 38% in non-survivors; P<0.001) and the absence of the left main coronary artery (3% survivors vs. 29% non-survivors; P=0.003) as culprit lesion in patients with cardiogenic shock was strongly associated with an improved survival rate. A second cardiac intervention was performed in seven patients (18%). Overall functional capacity of shock survivors was good. At final follow-up, 80% of the survivors were completely asymptomatic. One patient had angina pectoris NYHA II, five patients dyspnoea NYHA class II. Exercise stress-test was performed in 24 of the 38 surviving patients, median exercise capacity was 100% (range 55-113%) of the age adjusted predicted value. In unselected patients with cardiogenic shock due to AMI, treatment with acute PTCA resulted in an in-hospital mortality of 36%, low late mortality and good functional capacity in long-term survivors. TIMI flow grade III after acute PTCA in patients with acute myocardial infarction complicated by cardiogenic shock was strongly associated with an improved survival rate whereas the left main coronary artery as culprit lesion was associated with worse outcome.

[Interventional treatment of acute myocardial infarct]

BACKGROUND

Randomised trials have shown that primary percutaneous angioplasty (PTCA) may offer advantages over thrombolysis in treating acute myocardial infarction (vessel patency is achieved more often, mortality and reinfarction rate are lower, cerebrovascular accidents are less frequent). Data from several foreign registries have been less clear. Up to now no registry data have been available for Switzerland. Data from registries are very important in planning optimal treatment under "real world" conditions.

METHOD

All patients receiving acute PTCA during the first 24 hours of acute myocardial infarction were prospectively included in a registry at a single centre. We assessed times until revascularisation, as well as clinical, angiographic and outcome data.

RESULTS

503 patients (age 59 +/- 12 years, 15% women) were included from 1. 1. 1995 to 30.6.2000. Primary PTCA was performed in 334 patients, and rescue PTCA in 169. Diabetes mellitus was present in 36% of the total. Multivessel disease was present in 61%, anterior infarction in 36%, and 16% were in cardiogenic shock before intervention. The pre-hospital delay was 2:12 h (median). In-hospital decision delay (hospital admission until contact to cardiologist) in patients with primary PTCA was 31 minutes (median). The time from vessel puncture to recanalisation was 19 minutes (median). 273 patients were transferred for coronary angiography and intervention by other hospitals (218 by ground ambulance, 55 per helicopter transfer). The total transfer time (calculated from time of decision to arrival in the catheterization laboratory) was 57 minutes (median). PTCA was successful angiographically in 97% and TIMI 3 flow was obtained in 93% of all patients. Hospital mortality was low in view of the high proportion of patients in cardiogenic shock prior to PTCA (mortality in shock patients was 33%). Mortality in patients without pre-existing cardiogenic shock was 2%.

CONCLUSION

Patients with acute myocardial infarction, especially high-risk patients, can be treated successfully by acute PTCA around the clock in Switzerland, in accordance with the strict international recommendations for time delays. The treatment results are similar to those in randomised trials. Transfer of patients from referral hospital is safe, with acceptable delays. Optimisation of the decision process and transport logistics may further improve outcome by reducing the total ischaemia time.

An uncommon cause of recurrent strokes: Tropheryma whippelii endocarditis

BACKGROUND

Cardiac involvement in Whipple's disease is not an uncommon phenomenon in autopsies, but its clinical occurrence is often overshadowed by gastrointestinal symptoms. We report a very atypical manifestation of this disorder.

SUMMARY OF REPORT

An extraordinary presentation of an extremely long-lasting, culture-negative endocarditis caused by Tropheryma whippelii is described, the clinical consequence of which has become apparent in recurrent strokes.

CONCLUSIONS

Cardiac involvement of Whipple's disease should always be considered in culture and serologically negative endocarditis. The polymerase chain reaction technique may be a useful tool to confirm a presumed diagnosis of T whippelii endocarditis and consequently to apply an effective treatment regimen.

The acute effects of transvenous biventricular pacing in a patient with congestive heart failure

The management of congestive heart failure remains an issue of great interest. Encouraging data emerged over the last 2 years supporting the use of multisite pacing in patients with severe congestive heart failure and intraventricular conduction delay. We present a case of acute biventricular pacing in a 81-year old man with dilated cardiomyopathy and symptomatic congestive heart failure. This novel form of pacemaker treatment resulted in a rapid hemodynamic and clinical improvement.

A double-blind, randomized study of the effect of immediate intravenous nitroglycerin on the incidence of postprocedural chest pain and minor myocardial necrosis after elective coronary stenting

BACKGROUND

Anginal chest pain without creatine kinase (CK) elevation is frequently observed in the first hours after coronary stenting. Possible causes of ischemic episodes are microembolism, side branch occlusion, coronary vasospasm, and disturbances of microvascular circulation. In a prospective, double-blind, randomized trial, we tested the effect of intravenous nitroglycerin on the incidence of angina and minor myocardial necrosis (MMN), as detected by cardiac troponin I increase, after elective coronary stenting.

METHODS AND RESULTS

One hundred patients were randomly assigned to intravenous nitroglycerin (group A: n = 50, goal dose 100 microgram/min) or placebo (group B: n = 50, NaCl 0.9%) during 12 hours after stenting. Patients with acute myocardial infarction, known intolerance to nitrates, and hemodynamic instability during angioplasty were excluded. The 2 groups were comparable in respect to baseline and interventional variables, except for age (group A: 60 +/- 9 years, group B: 56 +/- 10 years; P =.04). The incidence of chest pain was not influenced by nitroglycerin (group A: 18%, group B: 22%; P = not significant). However, the occurrence of MMN was significantly reduced by nitroglycerin (group A: 5%, group B: 19%, P =.036). A rise in CK with significant CK-MB fraction was observed in only 2 patients in group B (both less than twice upper limit). Only 4 of the 10 patients with MMN also had chest pain.

CONCLUSIONS

Routine use of intravenous nitroglycerin after coronary stenting significantly reduced the occurrence of minor myocardial necrosis. However, the incidence of postprocedural chest pain remained unchanged.

Hospital transfer for primary coronary angioplasty in high risk patients with acute myocardial infarction

OBJECTIVE

To investigate the feasibility, safety, and associated time delays of interhospital transfer in patients with acute myocardial infarction for primary percutaneous transluminal coronary angioplasty (PTCA).

DESIGN AND PATIENTS

Prospective observational study with group comparison in a single centre. 68 consecutive patients with acute myocardial infarction transferred for primary PTCA from other hospitals (group A) were compared with 78 patients admitted directly to the referral centre (group B).

MAIN OUTCOME MEASURES

Patient groups were analysed with regard to baseline characteristics, time intervals from onset of chest pain to balloon angioplasty, hospital stay, and follow up outcome.

RESULTS

Patients in group A presented with a higher rate of cardiogenic shock initially than patients in group B (25% v 6%, p = 0.01) and had been resuscitated more frequently before PTCA (22% v 5%, p = 0.01). No deaths or other serious complications occurred during interhospital transfer. Median transfer time was 63 (range 40-115) minutes for helicopter transport (median 42 (28-122) km, n = 14), and 50 (18-110) minutes by ground ambulance (median 8 (5-68) km, n = 54). The median time interval from the decision to perform coronary arteriography to balloon inflation was 96 (45-243) minutes in group A and 52 (17-214) minutes in group B (p = 0.0001). In transferred patients (group A) the transportation associated delay and the longer in-hospital median decision time (50 (10-1120) minutes in group A v 15 (0-210) minutes in group B, p = 0.002) concurred with a longer total period of ischaemia (239 (114-1307) minutes in group A v 182 (75-1025) minutes in group B, p = 0.02) since the beginning of chest pain. Success of PTCA (TIMI 3 flow in 95% of all patients), in-hospital mortality (7% v 9%, mortality for patients not in cardiogenic shock 0% v 4%), and follow up after median 235 days was similarly favourable in groups A and B, respectively. Only one hospital survivor (group A) died during follow up.

CONCLUSION

Interhospital transport for primary PTCA in high risk patients with acute myocardial infarction is safe and feasible within a reasonable period of time. Short and medium term outcome is favourable. Optimising the decision process and transport logistics may further improve outcome by reducing the total time of ischaemia.

Dual chamber pacing with a single-lead DDD pacing system

The successful application of single-lead VDD pacing during the last few years has generated the idea of single-lead DDD pacing. Preliminary data from several single-lead VDD studies attempting to pace the atrium by a floating atrial dipole are unsatisfactory, causing an unacceptably high current drain of the device. We studied the feasibility as well as the short- and long-term stability of atrioventricular sequential pacing, using a new single-pass, tined DDD lead. In eight consecutive patients (age 73+/-16 years) with symptomatic higher degree AV block and intact sinus node function, this new single-pass DDD lead was implanted in combination with a DDDR pacemaker. Correct VDD and DDD function was studied at implantation; at discharge; and at 1, 3, and 6 months of follow-up. At implant, the atrial stimulation threshold was 0.6+/-0.1 V/0.5 ms. During follow-up, the atrial pacing thresholds in different every day positions averaged 2.1+/-0.5 V at discharge, 2.9+/-0.5 V at 1 month, 3.8+/-0.4 V at 3 months, and 3.4+/-0.4 V at 6 months (pulse width always 0.5 ms). The measured P wave amplitude at implantation was 4.5+/-2.2 mV; during follow-up the telemetered atrial sensitivity thresholds averaged 2.1+/-0.3 mV. Phrenic nerve stimulation at high output pacing (5.0 V/0.5 ms) was observed in three (38%) patients at discharge and in one (13%) patient during follow-up; an intermittent unmeasurable atrial lead impedance at 3 and 6 months follow-up was documented in one (13%) patient. This study confirms the possibility of short- and long-term DDD pacing using a single-pass DDD lead. Since atrial stimulation thresholds are still relatively high compared to conventional dual-lead DDD pacing, further improvements of the atrial electrodes are desirable, enabling lower pacing thresholds and optimizing energy requirements as well as minimizing the potential disadvantage of phrenic nerve stimulation.

Epicardial, biatrial synchronous pacing for prevention of atrial fibrillation after cardiac surgery

About 30% of patients develop AF after open heart surgery. Biatrial synchronous pacing (BSP) has been shown to promote sinus rhythm in patients with paroxysmal AF refractory to drug therapy. We conducted a prospective, randomized study to test the effect of BSP via epicardial electrodes on the incidence of AF after heart surgery, as compared to conventional therapy. To apply BSP, we attached two epicardial electrodes to the right and one to the left atrium. Immediately following surgery, BSP was initiated in the AAI-Mode at a rate of 10 beats/min above the underlying rhythm (maximum 110 beats/min) and continued for 3 days, during which the rhythm was continually monitored. After 21 (age 63 +/- 9 years) of the planned 200 patients, the study was prematurely aborted because of the proarrhythmic effect of BSP: 6 of the 12 patients treated with BSP developed sensing failure (P amplitude < 1 mV), which provoked AF in 5 of these 6 patients. BSP was discontinued due to diaphragmal stimulation in two patients and due to ventricular stimulation by a dislocated left atrial electrode in one patient. Two patients in the control group (n = 9) developed AF. Using the available standard technology, BSP via epicardial electrodes is not suitable to suppress AF after heart surgery, primarily due to postoperative deterioration of atrial sensing and its profibrillatory effect. In patients requiring atrial pacing after heart surgery, sensing thresholds must be closely monitored to prevent induction of AF.

[Acute myocardial infarct in Switzerland: results from the PIMICS Heart Infarct Register. PIMICS Project (Prospective Ischemia Myocardial Infarction Captopril Survey)]

The aim of the PIMICS project was to create, for the first time in Switzerland, a registry of data concerning epidemiology and therapy in patients hospitalised for acute myocardial infarction covering all regions of the country. During 1995/96 73 Swiss hospitals of all categories took part in the PIMICS project. The ratio between males and females in the 3877 registered patients was 2.6:1 (2791 men vs. 1086 women). Female patients were significantly older than males (70.4 +/- 12.0 years vs. 63.4 +/- 12.6 years; p < 0.0001). The prevalence of risk factors differed between men and women: significantly more women had hypertension or diabetes, whereas smoking was more prevalent in males. The median delay between onset of symptoms and arrival at the hospital was 5.5 hours. Thrombolysis and primary angioplasty were more frequently performed in men (40.4% vs. 31.2% in women, p < 0.0001, and 5.7% in men vs. 3.5% in women, p = 0.005 respectively). During the acute phase males were treated more frequently with betablockers. The overall in-hospital mortality was 9.1%. It was significantly higher in female patients (13.5% vs. 7.4% in men; p < 0.0001) and in patients with reinfarction (14.5% vs. 7.1%; p < 0.0001). The mean hospital stay was 12.6 +/- 5.3 days. Only 7.7% of all patients with acute myocardial infarction were discharged within 6 days. At discharge, 51.7% were treated with betablockers and 69.3% with aspirin; 44.8% received ACE-inhibitors and only 13.8% lipid-lowering drugs. Follow-up measures such as coronary angiography and/or angioplasty or bypass surgery were performed significantly more often in males (45.0% vs. 32.9%; p < 0.0001). Likewise, men were more frequently assigned to a rehabilitation program than women (38.2% vs. 32.9%; p = 0.0004). The pre-hospital delay in patients with acute myocardial infarction remains too long. Primary and secondary prevention should be intensified in high risk groups, particularly in females. Thrombolysis and primary angioplasty as mainstays of treatment in acute myocardial infarction are generally used too sparingly, especially in women. With such measures the hospital stay could be shortened further.

A new approach for DDD(R) pacing using a single-pass DDD lead

Short- and long-term results for DDD pacing using a single-pass DDD lead are presented for 3 patients. Single-lead DDD pacing is feasible and may provide major advantages by eliminating the necessity of a second lead.

Intermittent pacemaker dysfunction caused by digital mobile telephones

OBJECTIVES

This study was designed to evaluate possible interactions between digital mobile telephones and implanted pacemakers.

BACKGROUND

Electromagnetic fields may interfere with normal pacemaker function. Development of bipolar sensing leads and modern noise filtering techniques have lessened this problem. However, it remains unclear whether these features also protect from high frequency noise arising from digital cellular phones.

METHODS

In 39 patients with an implanted pacemaker (14 dual-chamber [DDD], 8 atrial-synchronized ventricular-inhibited [VDD(R)] and 17 ventricular-inhibited [VVI(R)] pacemakers), four mobile phones with different levels of power output (2 and 8 W) were tested in the standby, dialing and operating mode. During continuous electrocardiographic monitoring, 672 tests were performed in each mode with the phones positioned over the pulse generator, the atrial and the ventricular electrode tip. The tests were carried out at different sensitivity settings and, where possible, in the unipolar and bipolar pacing modes as well.

RESULTS

In 7 (18%) of 39 patients, a reproducible interference was induced during 26 (3.9%) of 672 tests with the operating phones in close proximity (<10 cm) to the pacemaker. In 22 dual-chamber (14 DDD, 8 VDD) pacemakers, atrial triggering occurred in 7 (2.8%) of 248 and ventricular inhibition in 5 (2.8%) of 176 tests. In 17 VVI(R) systems, pacemaker inhibition was induced in 14 (5.6%) of 248 tests. Interference was more likely to occur at higher power output of the phone and at maximal sensitivity of the pacemakers (maximal vs. nominal sensitivity, 6% vs. 1.8% positive test results, p = 0.009). When the bipolar and unipolar pacing modes were compared in the same patients, ventricular inhibition was induced only in the unipolar mode (12.5% positive test results, p = 0.0003).

CONCLUSION

Digital mobile phones in close proximity to implanted pacemakers may cause intermittent pacemaker dysfunction with inappropriate ventricular tracking and potentially dangerous pacemaker inhibition.

VDD(R) pacing: short- and long-term stability of atrial sensing with a single lead system

BACKGROUND

Recent studies have shown that the atrial signal can reliably be sensed for VDD(R) pacing via atrial floating electrodes incorporated in a single-pass lead. However, there remains concern about the long-term stability of atrial sensing and proper VDD function under real-life conditions. This study investigated the long-term reliability of atrial sensing and atrioventricular synchronous pacing using a new single lead VDD(R) pacing system.

METHODS AND RESULTS

In 20 consecutive patients (ages 71 +/- 14 years) with normal sinus node function and high-degree heart block, a single lead VDD(R) pacemaker (Unity, Intermedics) was implanted. Atrial sensing was studied at implantation, at discharge, and at 1, 3, 6, 12, and 18 months of follow-up. At implant, the measured P wave amplitude was 2.3 +/- 1.2 mV. By telemetry, the atrial sensing threshold was 0.79 +/- 0.41 mV at discharge, 0.75 +/- 0.43 mV at 1 month, 0.73 +/- 0.43 mV at 3 months, 0.76 +/- 0.41 mV at 6 months, 0.79 +/- 0.41 mV at 12 months, and 0.77 +/- 0.35 mV at 18 months of follow-up (P = NS). Appropriate VDD pacing was assessed by the percentage of correct atrial synchronization (PAS = atrial triggered ventricular paced complexes divided by total number of ventricular paced complexes) during repeated Holters. PAS was 99.99% +/- 0.01% at 1 month, 99.99% +/- 0.02% at 3 months, and 99.98% +/- 0.05% at 12 months of follow-up (P = NS). No atrial oversensing with inappropriate ventricular pacing was observed, neither during isometric arm exercise testing nor spontaneously during Holter monitoring.

CONCLUSION

The long-term stability of atrial sensing with almost 100% correct atrial synchronous tracking and the lack of inappropriate pacing due to atrial oversensing make the new Unity VDD(R) system a highly reliable single lead pacing system. In view of the lower costs and the ease of single lead implantation, this system may offer an interesting alternative to DDD pacemakers in patients with normal sinus node function.

Prolonged decrease in heart rate variability after elective hip arthroplasty

The pattern of postoperative heart rate variability may provide insight into the response of the autonomic nervous system to anaesthesia and surgery. We have obtained spectral (fast Fourier transform) and non-spectral indices of heart rate variability from electrocardiographic recordings, sampled during continuous perioperative Holter monitoring in 15 otherwise healthy patients with an uncomplicated postoperative course, undergoing elective hip arthroplasty with either spinal or general anaesthesia. In both groups, total spectral energy (0.01-1 Hz), low-frequency spectral energy (0.01-0.15 Hz) and high-frequency spectral energy (0.15-0.40 Hz) decreased after surgery to 32% (95% confidence interval (CI) 10.5; P < 0.01), 29% (95% CI 12.5; P < 0.01) and 33% (95% CI 12.5; P < 0.01) of their preoperative values, respectively, and these indices remained suppressed for up to 5 days. Non-spectral indices decreased to a similar extent. These findings indicate a substantial and prolonged postoperative decrease in both parasympathetic and sympathetic influence on the sinus node.