Phased multipolar radiofrequency pulmonary vein isolation is as effective and safe as conventional irrigated point-to-point ablation. A prospective randomised 1-year implantable cardiac monitoring device follow-up trial.

PURPOSE: Pulmonary vein isolation (PVI) is conventionally performed using 3D electroanatomical mapping to guide point-to-point ablation. The Pulmonary Vein Ablation Catheter (PVAC)® is a phased multipolar ablation (PMRA) catheter designed for rapid PVI using radiological anatomical information. Comparison of these methods of PVI using continuous beat-to-beat monitoring was undertaken. METHODS: Fifty patients with drug-refractory, symptomatic paroxysmal atrial fibrillation (PAF) were recruited. Patients all had REVEAL® XT ILR or a DDDRP permanent pacemaker (PPM) inserted prior to PVI. PPM was programmed to monitoring mode (ODO). Patients were randomised 1:1 to undergo PVI with either point-to-point irrigated radiofrequency ablation (Conv) or PMRA technology. Follow-up was performed at 0, 3, 6, 9, and 12 months using Holter downloads to assess arrhythmia burden. Outcomes were examined following a 3-month blanking period. RESULTS: The AF burden pre-ablation, at 3-month and at 12-month post-ablations, was not significantly different (pre-ablation AF burdens (mean ± SE) Conv 16.6 ± 5.0%, PVAC 17.0 ± 5.6 %, 3 months Conv 4.0 ± 1.6 %, PVAC 4.7 ± 1.5%, 12 months Conv 4.3 ± 2.3%, PVAC 3.8 ± 1.5%). In both groups, there was a significant reduction in AF burden from pre-ablation (at 3 months p = 0.01, p = 0.04, at 12 months p = 0.04, p = 0.03 for Conv and PMRA groups, respectively). Overall success rate for zero AF recurrence at 12 months was 54%. CONCLUSION: PMRA PVI is comparable to conventional technology for AF extinction at 1 year. The PMRA is as safe as conventional technology but enables the operator to perform the procedure faster. Device monitored success rates were lower than other studies not utilising such intensive monitoring confirming that sporadic ECG monitoring is not sufficient to detect all AF recurrence. TRIAL REGISTRATION: NCT01095770. URL: https://clinicaltrials.gov/ct2/show/NCT01095770.

The natural history of atrial fibrillation in patients with permanent pacemakers: is atrial fibrillation a progressive disease?

OBJECTIVES: Atrial fibrillation (AF) is thought to be a progressive arrhythmia, starting with short paroxysmal episodes, until eventually, it becomes permanent. Evidence for this is limited to studies with short follow-up or with minimal cardiac rhythm monitoring. We utilised the continuous rhythm monitoring capabilities of implanted pacemakers to define better the natural history of AF. METHODS: The study included 356 patients with pacemaker devices capable of continuous atrial rhythm monitoring (186 male, mean age (± SD) 79.5 ± 8.9 years). All clinical records, including history/physical examination reports, laboratory results, ECGs and Holter monitoring data were reviewed. Patients were included if AF episodes >30 s were documented. Permanent pacemaker diagnostic data were reviewed at least every 12 months. ACC/AHA/ESC guidelines were used to define AF episodes as paroxysmal, persistent or long-standing persistent/permanent. RESULTS: Study follow-up period (± SD) was 7.2 ± 3.1 years. Over the study period, 179 of 356 patients (50.3 %) had at least one episode of persistent AF. Of the 356 patients, 314 (88.2 %) had paroxysmal AF and 42 (11.8 %) had persistent AF at the time of diagnosis. The predominant AF subtype, at latest follow-up, was paroxysmal for 192 patients (53.9 %), persistent for 77 (21.6 %) and long-standing persistent/permanent for 87 (24.4 %). Univariable predictors of progression to persistent AF were (1) male gender, (2) increasing left atrial diameter (LAD), (3) reduced atrial pacing (AP) and (4) increasing ventricular pacing. CONCLUSIONS: Although many patients with AF will have persistent episodes, long-term continuous pacemaker follow-up demonstrates that the majority will have a paroxysmal, as opposed to persistent, form of the arrhythmia.

Remote monitoring of cardiovascular disease: great promise, but do not forget the patient!

After more than 20 years, the conflict of interest (COI) movement has failed to substantiate its central claim that interactions between physicians, researchers and the medical products industry cause physicians to make clinical decisions that are adverse to the best interests of their patients. The COI movement's instigators have produced no solid evidence of harm commensurate with their extravagant allegations. At the same time, they have diverted resources away from more worthwhile pursuits, such as basic and applied medical research, clinical care and medical education towards onerous compliance exercises and obtrusive laws. Perhaps worst of all, they have made it respectable to ignore the epistemological foundations of medical science, diverting attention away from the scientific merit of the information presented and focusing it instead on the identity and motives of those who present the information.

It's good to talk! Changes in coronary revascularisation practice in PCI centres without onsite surgical cover and the impact of an angiography video conferencing system.

INTRODUCTION: Percutaneous coronary intervention (PCI) activity has increased more than 6 fold in the last 15 years. Increased demand has been met by PCI centres without on-site surgical facilities. To improve communication between cardiologists and surgeons at a remote centre, we have developed a video conferencing system using standard internet links. The effect of this video data link (VDL) on referral pattern and patient selection for revascularisation was assessed prospectively after introduction of a joint cardiology conference (JCC) using the system. METHODS: Between 1st October 2005 and 31st March 2007, 1346 patients underwent diagnostic coronary angiography (CA). Of these, 114 patients were discussed at a cardiology conference (CC) attended by three consultant cardiologists (pre-VDL). In April 2007, the VDL system was introduced. Between 1st April 2007 and 30th September 2008, 1428 patients underwent diagnostic CA. Of these, 120 patients were discussed at a JCC attended by four consultant cardiologists and two consultant cardiothoracic surgeons (post-VDL). Following case-matching for patient demographics and coronary artery disease (CAD) severity and distribution, we assessed the effect upon management decisions arising from both the pre- and post-VDL JCC meetings. RESULTS: When comparing decision-making outcomes of post-VDL JCC with pre-VDL CC, significantly fewer patients were recommended for PCI (36.8% vs. 17.2% respectively, p = 0.001) and significantly more patients were recommended for surgery (21.1% vs. 48.4% respectively, p < 0.001). There were no significant differences in waiting times for PCI following JCC discussion; however, waiting times for surgical revascularisation were significantly reduced (140.9 ± 71.8 days vs. 99.4 ± 56.6 days respectively, p = 0.045). CONCLUSIONS: The VDL system provides a highly practical method for PCI centres without onsite surgical cover to discuss complex patients requiring coronary revascularisation and significantly increases the number of patients referred for surgical revascularisation rather than PCI.

First time and repeat cardioversion of atrial tachyarrhythmias - a comparison of outcomes.

INTRODUCTION: Repeat cardioversion may be necessary in over 50% of patients with persistent atrial fibrillation (AF), but identifying responders remains challenging. This study evaluates the long-term success of direct current cardioversion (DCCV) and the clinical and echocardiographical parameters that influence them, in over 1000 sedation-cardioversion procedures undertaken at Eastbourne General Hospital between 1996 and 2006. METHODS: A total of 770 patients of mean age (SD) 70.1(10.1) underwent 1013 DCCVs (first n = 665, repeat n = 348) for atrial tachyarrhythmias from 1996 to 2006. Time to persistent arrhythmia recurrence was compared between first and multiple DCCV, and the effect of age, gender, presence of heart disease, left atrial size, fractional shortening, arrhythmia duration, anti-arrhythmic drug therapy (AAD) and other concomitant cardiac medication was evaluated using the Kaplan-Meier method and Cox's Proportional-hazards model. RESULTS: In all, 33% of first and 29% of repeat DCCVs were in sinus rhythm (SR) at 12 months (m). There was no difference in median time to arrhythmia recurrence (SE) between first and multiple procedures: 1.5 +/- 0.1 m (1.3-1.7) and 1.5 +/- 0.0 m (1.4-1.6) respectively, p = 0.45. AAD use was significantly higher, arrhythmia duration shorter and more diabetic patients underwent repeat procedures. Amiodarone, OR 0.56, p = 0.04, sotalol, OR 0.61, p = 0.02 and arrhythmia duration, < 6 m, OR 0.72, p = 0.03 were independent predictors of improved outcome in first procedures only. In patients undergoing first procedures on amiodarone or sotalol, median time to arrhythmia recurrence was longer and 12 m SR rates higher, 6.0 +/- 2.4 m (42%) than those who had a repeat procedure on the same medication, 1.5 +/- 0.1 m (33%), p = 0.06. CONCLUSIONS: The efficacy of first and subsequent DCCV procedures is similar, achieving a similar proportion of SR maintenance at 1 year. However, the benefits of AAD therapy are the greatest following first time procedures. Concomitant AAD therapy should be considered for all first time procedures for persistent AF.

A randomised controlled trial comparing StarClose and AngioSeal vascular closure devices in a district general hospital--the SCOAST study.

AIMS: AngioSeal and StarClose are vascular closure devices (VCDs) that can be used following cardiac catheterisation via the femoral artery to achieve haemostasis. Both devices have been demonstrated to be superior to conventional manual pressure, which reduce time to haemostasis and time to patient ambulation. We sought to compare these devices in a prospective, randomised trial. METHODS: Patients undergoing elective coronary angiography were randomised to receive either AngioSeal VIP or StarClose VCD with immediate postprocedure mobilisation. Bruising was recorded at 30 min, 60 min and at 1 week postprocedure. Patient satisfaction surveys were taken at 1 h and 1 week postprocedure. Complications for both groups were compared. RESULTS: Four hundred and one patients were included. Arteriotomy closure was achieved in 144 of 208 (69.2%) patients randomised to AngioSeal and 134 of 193 (69.3%) patients randomised to StarClose (p = ns). There was no significant bruising in either group at either 30 or 60 min postprocedure. However, at 1 week, there was significantly more bruising in the AngioSeal group than the StarClose group (63.1 vs. 38.5cm2, p = 0.02). Patient satisfaction and pain perception with the procedure at closure were not significantly different between the groups. Deployment success and instant mobilisation rates were significantly lower for junior, as compared with senior, operators. CONCLUSION: Achievement of haemostasis is similar with both AngioSeal and StarClose. The StarClose vascular closure device results in significantly less bruising at 1 week postprocedure as compared with AngioSeal, with no significant differences in complication rates. Patients' pain perception and satisfaction are similar with both VCDs.

A randomised controlled trial comparing the routine use of an Angio-Seal STS device strategy with conventional femoral haemostasis methods in a district general hospital.

Femoral artery closure devices reduce the time to haemostasis and ambulation. Most district general hospitals (DGHs) now perform day case angiography on site. The purpose of this study was to assess the Angio-Seal self-tightening suture (STS) device in comparison with manual compression in this environment. A prospective randomised controlled trial was undertaken comparing the Angio-Seal STS device with manual pressure recording complications, time from end of procedure and patient satisfaction in a DGH setting. Angiography lists of 206 patients undergoing day case diagnostic cardiac catheterisation with a five French sheath at a DGH were randomised by intention to treat to receive either manual compression or a six French Angio-Seal STS device. Time from sheath removal to mobilisation, complication rate and patient satisfaction were compared. There were no significant differences between the two groups in terms of demographics (manual compression: Angio-Seal; male (%) 58 vs. 57, age (years) 65.4 vs. 66.3, body mass index (kg/m(2)) 27.7 vs. 27.5). Despite randomisation, only 74 of 107 patients in the Angio-Seal group actually had a device deployed. Angio-Seal use was associated with significantly shorter times to mobilisation (87.6 vs. 144.1 min; p < 0.001), significantly less bruising (bruise size at 1 week (28.5 vs. 82.5 cm(3); p < 0.01) and no increase in vascular complications. In addition, patients were more satisfied with Angio-Seal devices in terms of length of immobility. The routine use of Angio-Seal closure devices result in earlier mobilisation, less bruising, increased patient satisfaction with no increase in other complications in comparison to manual pressure.

A randomised prospective comparison of three protocols for head-up tilt testing and carotid sinus massage.

INTRODUCTION: Head-up tilt testing is an important tool in the diagnosis of syncope. Several different protocols are in use. This study aimed to compare three different protocols in an unselected population of patients with recurrent unexplained syncope and to assess long-term outcome using conventional tilt-directed management or implantable loop recorder (Reveal Plus)-directed management, allowing evaluation of the sensitivity and specificity of the technique. METHODS: Patients with recurrent unexplained syncope were randomized to one of three tilt protocols: Drug-free--70 degree tilt, 45 min, CSM at 5 and 45 min. GTN--70 degree tilt, 35 min, CSM at 5 min, 400 microg of glyceryl trinitrate spray administered sublingually at 20 min. Adenosine--70 degree tilt, 5 min, CSM when blood pressure is stable in upright position, adenosine bonus at 150 microg/kg after CSM. Tilts were terminated at the onset of syncope, when systolic BP reached 60 mm Hg, or in the presence of prolonged hypotension (> 3 min systolic BP < 80 mm Hg). Appropriate therapies were commenced according to the result of the tilt test. All patients without a definite indication for immediate cardiac pacing (asystolic tilt) were randomized to conventional management or ILR implantation. Recurrent syncopal events were compared to tilt outcome, allowing estimation of sensitivity and specificity. RESULTS: Of 214 patients, aged 68+/-18 years, 55% were female, with a median of three previous syncopes. 13 patients received pacemakers due to asystolic syncope during tilt testing. The proportion of VASIS classification diagnoses was similar with each protocol; however more positive diagnoses resulted from the GTN protocol (p=0.0013). 47% of patients achieved a diagnosis with tilt testing. We were able to correlate a subsequent spontaneous syncope to tilt result in 36 patients (18%). Heart rate during a spontaneous event was similar to that obtained during tilt testing (+/- 10%) in 55% of cases. Sensitivities for combined protocols, adenosine, GTN, and drug-free protocols were 50%, 50%, 100%, and 21%, respectively. Specificities were 85%, 100%, 75%, and 71%, respectively. CONCLUSIONS: A high diagnosis rate for unexplained syncope can be achieved with tilt testing. The GTN protocol resulted in significantly more diagnoses than the other compared protocols with good sensitivity and adequate specificity. Sensitivity of the drug-free tilt test was lower than drug-augmented tilt testing.

Use of implantable loop recorders in the diagnosis and management of syncope.

BACKGROUND: Syncope is a common, disabling symptom. The most useful data for diagnosing and managing syncope is the recording of physical parameters such as the ECG and blood pressure during a spontaneous event. Implantable loop recorders (ILR) provide an opportunity to record ECG data from a spontaneous event. The purpose of the Eastbourne Syncope Assessment Study (EaSyAS) was to investigate the impact of ILRs on an unselected population of syncopal patients presenting acutely to our institution. METHODS: All patients presenting acutely with recurrent, unexplained syncope over a 16-month period, were randomised after a basic clinical workup to receive the Reveal Plus ILR or conventional investigation. All patients were followed up for at least 6 months (mean 276+/-134 days) following randomisation. The primary outcome measure was time to ECG diagnosis. RESULTS: Four hundred twenty-one patients presented, 201 were eligible, median age 74 years (interquartile range 61-81 years), 54% female, with a median of three previous syncopes (IQ range 2-6). Thirty-three percent of ILR patients and 4% of conventional patients had an ECG diagnosis (hazard ratio 8.93, 95% CI 3.17-25.2, p < or = 0.0001). Introduction of ECG-directed therapy was quicker for ILR patients (hazard ratio 7.9, 95% CI 2.8-22.3, p < 0.0001). ILR patients had fewer post-randomisation investigations and fewer hospital days, resulting in a saving of costs, 406 UK pounds versus 1210 UK pounds (mean difference 809 UK pounds, 95% CI 123-2730 UK pounds). There was no difference in the number of subsequent syncopal episodes, mortality, or quality of life. CONCLUSIONS: LR significantly increased the rate of diagnosis in an unselected Western population with recurrent syncope. There was a significant decrease in the rates of hospitalisation and investigation in patients receiving an ILR.

Does the use of a syncope diagnostic protocol improve the investigation and management of syncope?

OBJECTIVES: To assess the efficacy of a protocol designed to improve the diagnosis and management of syncope. DESIGN: Prospective outcome analysis of all patients presenting with syncope for the 12 month period from 1 November 2000 to 31 October 2001, compared with a retrospective study of all patients presenting with syncope during the calendar year 1998. Use of the protocol commenced in September 2000. SETTING: Eastbourne District General Hospital, serving a population of approximately 250 000; 25% are older than 65 years. SUBJECTS: 421 consecutive patients presenting with syncope, investigated prospectively in January 2000 and compared with 660 patients retrospectively analysed for the calendar year 1998. RESULTS: In 1998, 71% of patients with syncope received a diagnostic classification. In January 2000 there was an appropriate diagnostic hypothesis for every patient. Ultimately a diagnosis was made for 78% of patients according to accepted criteria (p = 0.003). Use of tests with the highest diagnostic effectiveness, such as tilt tests, increased in 2001 and many tests were used more appropriately (such as echocardiography). However, non-diagnostic tests were still frequently used (such as chest radiography, electroencephalography, and carotid Doppler studies). Costs of investigation and hospital stay rose from pound 611 to pound 1384 (euro;874 to euro;1980) per patient (p < 0.001), with cost per diagnosis increasing from pound 870 (euro;1245) in 1998 to pound 1949 (euro;2790) (p < 0.001). CONCLUSION: The syncope protocol improved diagnosis and the use of appropriate investigations. However, significant inappropriate investigation and hospital admission still occurred. The protocol allowed reliable triage of syncopal patients into high and low risk groups.

Safety, effectiveness and cost efficacy of diagnostic electrophysiology and radiofrequency ablation in a district general hospital.

Electrophysiological studies (EPS) are now being performed in district general hospitals (DGH) in the UK. In order to audit our results, a prospective database was established for all patients undergoing EPS and radiofrequency (RF) ablation at Eastbourne District General Hospital, East Sussex. Between 1 January 1997 and 1 July 2000, 300 EPS procedures were performed, resulting in 155 RF ablations. The average RF ablation procedure time was 119.3 minutes with an average fluoroscopy time of 19.1 minutes. Cost per RF ablation procedure was 1166.79 Pounds excluding use of facilities, pacemaker devices, medical nursing and radiography staffing costs. The overall success rate for RF ablation was 93.6% with a major complication rate of 0.6%, a total complication rate of 3.9% and no associated mortality. We have shown that RF ablation can be performed safely, effectively and economically in a DGH setting with a high rate of success and a low complication rate.

How many people with heart failure are appropriate for biventricular resynchronization?

AIMS: Increasing evidence exists suggesting that biventricular pacing improves outcome and symptoms in severe heart failure if various selection criteria are fulfilled. It is unsure how many people might benefit from this therapy. Our aim was to provide such data. METHODS AND RESULTS: Over one calendar year all patients admitted to a large U.K. District General Hospital, that were classified with a diagnosis of heart failure, were audited. The selection criteria were; (1) severe heart failure (NYHA class III or IV), (2) heart failure due to a dilated cardiomyopathy, (3) QRS duration greater than 120 ms or (4) the presence of a bundle branch block pattern. Subjects were divided into those in sinus rhythm to determine those who would be suitable for atrially synchronized biventricular pacing and those with an abnormally long PR interval (>210 ms) who might additionally benefit from improved atrioventricular synchrony. 1042 patients were coded with heart failure. 721 fulfilled diagnostic criteria and were studied. 202 (28%) had severe heart failure, 178 (25%) had a QRS of at least 120 ms, 437 (61%) had an ischaemic cardiomyopathy, 176 (24%) an idiopathic cardiomyopathy and 433 (60%) were in sinus rhythm. Overall mortality at the time of census was 29%. 43 patients were suitable for biventricular pacing with a further 29 atrial patients fibrillation who might benefit from biventricular pacing alone. CONCLUSION: Using our criteria, approximately 10% of an unselected group of heart failure admitted to a typical U.K. district general hospital over a calendar year would be appropriate for biventricular pacing. This represents a large number of patients who might derive benefit from this new therapy.

Atrial permanent pacing for sinus node dysfunction with absent right superior vena cava.

In patients with sinus node dysfunction and normal atrioventricular conduction, single chamber atrial pacing (AAI or AAIR mode) represents the most physiological treatment. Sinus node dysfunction is recognised in association with an absent right superior vena cava, and we present a case in which complete resolution of symptoms was achieved with endocardial atrial permanent pacing.

The effect of atrio-ventricular delay programming in patients with DDDR pacemakers.

Modern DDDR (dual chamber universal, rate responsive) pacemakers are complex, hugely capable devices incorporating new features that theoretically should enhance haemodynamics and therefore quality of life. Ten patients (mean age 48 years) with chronotropic incompetence and high grade A-V block had activity sensing DDDR devices implanted and underwent a randomized double-blind crossover assessment of rate responsive and different fixed atrio-ventricular delay (AVD) settings during 2 weeks of out-of-hospital activity in DDDR mode. Subjective assessment showed improved 'general wellbeing' and preference for 175 ms rate responsive AVD (P less than 0.01) or 125 ms fixed AVD (P less than 0.05). The longest fixed AVD setting (250 ms) was least acceptable and had increased symptom prevalence (P less than 0.02). Perceived exercise capacity and exercise treadmill tolerance was not significantly different at any setting in DDDR mode but was less in DDD mode. Echocardiographically derived stroke distance was greater at 125 ms AVD than 250 ms at 100 b.min-1 (P less than 0.05) but did not differ at slower heart rates at any AVD. Colour Doppler assessed mitral and tricuspid regurgitation was greatest at 250 ms AVD at all heart rates but did not correlate with increased symptomatology. Stroke distance evaluated from the mitral inflow velocity profile allows improved AVD programming during DDDR pacing. Rate adaptive A-V delay is a useful feature during DDDR pacing.

Open access exercise electrocardiography: a service to improve management of ischaemic heart disease by general practitioners.

An initial study of the use of open access exercise electrocardiography by general practitioners (GPs) in South East Kent showed that patient selection and interpretation of test results was frequently incorrect. After issuing guidelines, modifying the request form and instituting registrar review of all requests, significant improvements in both referral pattern, result interpretation and patient management have resulted. Forty-nine GPs requested 110 exercise tests during 1988/89. Twelve per cent were not undertaken after discussion with the referring practitioner. Eighty-four per cent of those tested would have been referred to the district general hospital cardiology outpatient department in the absence of open access exercise electrocardiography service. Six per cent of patients were referred directly for invasive investigation. Thirty-five per cent were referred to the district general hospital cardiology outpatient department, whilst 42% were spared hospital referral based on the result of the investigation. Better use of the modified service was suggested by: referral of fewer patients with non-cardiac chest pains (P = 0.002); more patients with a moderate pre-test probability of ischaemic heart disease (P less than 0.05); fewer inappropriate requests (P less than 0.01); and fewer inappropriately undertaken tests (P less than 0.001) than in the previous study. All patients with strongly positive test results were appropriately managed. Open access exercise electrocardiography in the format investigated is potentially a cost-effective and useful tool to improve diagnosis and management of heart disease by GPs.

Patent foramina ovale in elderly stroke patients.

Fifty elderly patients who had suffered cerebrovascular incidents from no obvious cause and 33 age-matched controls were investigated for the presence of a patent foramen ovale by contrast 2-dimensional echocardiography at rest and after the Valsalva manoeuvre. Right-to-left shunting was found in only one patient and in none of the controls. This finding is in contradistinction to young adult stroke patients in whom the prevalence of a haemodynamically significant patent foramina ovale is high. Paradoxical embolism is an uncommon cause of stroke in the elderly.

Supraventricular tachycardia control with Tachylog II: long-term follow-up.

Ten patients aged 16-63 years (mean 36.3) had the Siemens P56T "Tachylog II" pacemaker implanted for treatment of drug refractory supraventricular tachycardia. The pacemaker incorporates a noninvasive electrophysiological study (EPS) facility and a sophisticated Holter function combined with a unique "learning" self-search antitachycardia algorithm. The Holter reveals that new tachycardias arise that are not previously detected at conventional EPS. The number of stimuli in the initiation sequences during noninvasive EPS proved highly variable, however, termination sequences remained constant in the long term. There was variability of timing of stimuli in the long term that was significantly greater for "new" tachycardias than for "original" arrhythmias. Long-term follow-up (at 1 month, 6 months, and 1 year) have shown that 90% of patients have good tachycardia control without the need for drugs. All patients confirm the acceptability of this pacemaker for control of their arrhythmias in the long term.

Comparison of the normal sinus node with seven types of rate responsive pacemaker during everyday activity.

The heart rate response of 59 patients aged 17-79 years implanted with seven different types of rate responsive pacemakers was evaluated during graded exercise treadmill testing and during standardised daily activities. The heart rate response in patients with pacemakers was compared with the chronotropic response in 20 healthy controls of similar age and sex distribution who performed identical protocols. All pacemaker types adequately simulated the control heart rate response during the graded exercise treadmill test except during the early stages of exercise. However, during everyday activities, the response of ventricular rate responsive (VVIR) pacemakers was varied. Activity sensing systems rapidly overresponded to staircase descent, to changes in walking speed, and to suitcase lifting with the pacemaker arm, and these systems did not respond to mental stress. "Physiological" sensors (QT and minute ventilation units) responded slowly to rapid changes in physiological demand. The QT pacemaker patients did respond to mental stress but showed a paradoxical increase in rate during the recovery phases of burst exercise protocols such as staircase ascent/descent and walking deceleration. Dual chamber pacemakers in VDD, DDD, and DDDR modes most closely simulated the normal chronotropic response during everyday activities. Graded exercise treadmill testing, in isolation, may not be the best way to asses or program the heart rate response in patients with the heart rate adaptive pacemakers because changes in heart rate during everyday activities may deviate considerably from the normal sinus response despite satisfactory simulation of the normal chronotropic response during treadmill testing.