Assessment of atrioventricular conduction in aortic valve disease

Risk Factors, Management, and Avoidance of Conduction System Disease after Transcatheter Aortic Valve Replacement

Transcatheter valve replacement (TAVR) is a rapidly developing modality to treat patients with aortic stenosis (AS). Conduction disease post TAVR is one of the most frequent and serious complications experienced by patients. Multiple factors contribute to the risk of conduction disease, including AS and the severity of valve calcification, patients' pre-existing conditions (i.e., conduction disease, anatomical variations, and short septum) in addition to procedure-related factors (e.g., self-expanding valves, implantation depth, valve-to-annulus ratio, and procedure technique). Detailed evaluation of risk profiles could allow us to better prevent, recognize, and treat this entity. Available evidence on management of conduction disease post TAVR is based on expert opinion and varies widely. Currently, conduction disease in TAVR patients is managed depending on patient risk, with minimal-to-no inpatient/outpatient observation, inpatient monitoring (24-48 h) followed by ambulatory monitoring, or either prolonged inpatient and outpatient monitoring or permanent pacemaker implantation. Herein, we review the incidence and risk factors of TAVR-associated conduction disease and discuss its management.

Ambulatory Electrocardiogram Monitoring in Patients Undergoing Transcatheter Aortic Valve Replacement: JACC State-of-the-Art Review

Transcatheter aortic valve replacement (TAVR) has changed the treatment of patients with severe aortic stenosis. However, the occurrence of conduction disturbances has not decreased significantly over time and remains the main drawback of the procedure. In addition, new-onset atrial fibrillation is the most frequent tachyarrhythmia during the hospitalization period and is associated with worse clinical outcomes. However, little is known regarding the incidence and clinical impact of arrhythmic events beyond the periprocedural TAVR period. Ambulatory electrocardiogram (AECG) monitoring has recently emerged as a tool to unravel the complex issue of arrhythmic disorders (bradyarrhythmias and tachyarrhythmias) before and after TAVR. To date, the preliminary results from the initial experience using AECG monitoring systems showed the safety, usefulness, and potential clinical implications of this diagnostic tool in TAVR recipients. This review provides an overview of the current status, clinical implications, and future perspectives of AECG monitoring in the TAVR setting.

Conduction disorders after aortic valve replacement: what is the real impact of sutureless and rapid deployment valves?

Background

Although sutureless and rapid deployment aortic valve replacement (SURD-AVR) has been associated with an increased rate of permanent pacemaker (PPM) implantation compared to conventional AVR (c-AVR), the predictors of new conduction abnormalities remain to be clarified. This study aimed to identify risk factors for conduction disorders in patients undergoing AVR surgery.

Methods

Data from 243 patients receiving minimally invasive AVR were prospectively collected. SURD-AVR was performed in 103 (42.4%) patients and c-AVR in 140 (57.6%). The primary endpoint was the occurrence of new-onset conduction disorders, defined as first degree atrioventricular (AV) block, advanced AV block requiring PPM implantation, left anterior fascicular block (LAFB), left bundle branch block (LBBB) and right bundle branch block (RBBB).

Results

The unadjusted comparison revealed that SURD-AVR was associated with a higher rate of advanced AV block requiring PPM when compared with c-AVR (10.5% vs. 2.1%, P=0.01). After adjusting for other measured covariates (OR: 1.6, P=0.58) and for the estimated propensity of SURD-AVR (OR: 5.1, P=0.1), no significant relationship between type of AVR and PPM implantation emerged. On multivariable analysis, preoperative first-degree AV block (OR: 6.9, P=0.04) and RBBB (OR: 6.9, P=0.03) were independent risk factors for PPM. Subgroup analysis of patients with normal preoperative conduction revealed similar incidence of PPM between SURD-AVR and c-AVR (1.3% vs. 1.9%, P=0.6). When compared with c-AVR, SURD-AVR was associated with a greater incidence of postoperative new onset LBBB (18.1% vs. 3.2%, P<0.001). This finding was confirmed after adjusting for the estimated propensity of SURD-AVR (OR: 6.3, P=0.009).

Conclusions

Our study revealed that the risk of PPM implantation in patients receiving surgical AVR is heavily influenced by the presence of pre-existing conduction disturbances rather than the type of valve prosthesis. Conversely, SURD-AVR emerged as an independent predictor for LBBB and was associated with an increased risk of PPM in patients presenting with RBBB.

Timing and evolution of advanced conduction disturbances in patients with right bundle branch block undergoing transcatheter aortic valve replacement

Aims

This study sought to determine the timing and evolution over time of advanced conduction disturbances (CDs) in patients with baseline right bundle branch block (RBBB) undergoing transcatheter aortic valve replacement (TAVR).

Methods and results

One hundred and ten consecutive patients with pre-existing RBBB were included (out of 1341, 8.2%). All arrhythmias during the hospitalization period were recorded. Follow-up was performed at 30 days, 1 year, and yearly thereafter. Conduction recovery and ventricular pacing percentage (VPP) was evaluated at 30 days in those patients with permanent pacemaker implantation (PPMI). Sixty-one (55.5%) patients suffered advanced CDs [97% complete or high-degree atrioventricular block (CHB/HAVB)], and the vast majority (98%) occurred within the first 3 days post-procedure (intraprocedural: 85%). Fifty-two (47.3%) patients had PPMI (vs. 11.0% in non-RBBB patients, P &lt; 0.001). Ventricular pacing percentage at 1 month was higher in patients with persistent-intraprocedural CHB/HAVB compared to those with transient-intraprocedural or post-procedural CHB/HAVB [99 (interquartile range, IQR 97–100)% vs. 72 (IQR 30–99)%, P = 0.02]. Complete recovery (VPP &lt; 1%) was observed in only one patient (2%) with CHB/HAVB. After hospital discharge, no symptomatic bradyarrhythmias or sudden death occurred within 30 days. Patients with pre-existing RBBB exhibited a higher risk of PPMI at 4-year follow-up (26% vs. 8% in non-RBBB patients, P &lt; 0.001).

Conclusion

In patients with pre-existing RBBB, the vast majority of advanced CDs occurred within the 3 days following TAVR, and most did not recover at 1-month, particularly those with intra-procedural persistent CHB/HAVB. These results should help to determine the hospitalization length and timing of PPMI in RBBB patients undergoing TAVR.

Patients with bicuspid aortic valves may be associated with infra-hisian conduction disease requiring pacemakers

BACKGROUND

Bicuspid aortic valves (BAVs) are associated with accelerated valvular dysfunction. Increasing rates of conduction system disease are seen in patients with calcific tricuspid aortic valves (TAVs). However, little is known regarding the extent of conduction disorders in BAV patients. We sought to determine the extent of infra-hisian conduction pathology among patients with BAVs undergoing EP studies.

METHODS

We prospectively analyzed patients presenting to the EP laboratory from 2006 to 2017 at our institution. Thirty-three BAV patients had measured HV intervals. Each individual was matched by age and gender to two control patients. Clinical characteristics were collected and compared, and patients followed for outcomes.

RESULTS

The BAV cohort had a mean age of 47.8 ± 17.2 years (range 19-76 years). Indications for referral to the EP lab in the BAV cohort included SVT ablation (n = 16), VT ablation (n = 10), and EP study for syncope, pre-syncope, or palpitations (n = 29). Patients with BAVs had a mean HV interval of 58.7 ms ± 18.6 ms, compared to a mean of 47.2 ms ± 9.6 ms for controls (p value = 0.0001). Over a 10-year follow-up period, 9 BAV patients (27%) went on to require permanent pacing compared to 6 patients (9%) in the control group (p value = 0.03).

CONCLUSION

Compared to patients with TAVs presenting for EP evaluation, individuals with BAVs have longer HV intervals and a significantly increased requirement for pacemaker therapy over long-term follow-up. Closer monitoring of progressive conduction system disease in BAV patients may be warranted.

Long-Term Electrocardiographic Changes and Clinical Outcomes of Transcatheter Aortic Valve Implantation Recipients Without New Postprocedural Conduction Disturbances

The objective of this study was to determine the long-term (>1 year) electrocardiographic (ECG) and clinical outcomes of patients without significant changes in their electrocardiogram after transcatheter aortic valve implantation (TAVI; including patients with pre-existing ECG abnormalities). Among 772 consecutive patients who underwent TAVI in our institution, 397 patients (51%) without new ECG changes were included. TAVI patients were divided into 2 groups according to the presence of pre-existing ECG-conduction disturbances (ECG-CD: 140 patients, non-ECG-CD: 257 patients). Clinical follow-up (median: 35 [22 to 57] months) was complete in all patients but 5 (1.2%), and ECG data were available in 291 patients (84.3% of patients at risk) at a median of 29 (20 to 50) months. In the non-ECG-CD group, most patients (79.8%) remained without significant ECG changes at follow-up, and 16.9% developed first-degree atrioventricular block and/or bundle branch block over time. The rate of permanent pacemaker (PPM) implantation at follow-up was 3.5% (1.1%/year) in the non-ECG-CD group versus 15.7% (5.5%/year) in the ECG-CD group (p <0.001). The presence of pre-existing CD was an independent predictor of PPM at follow-up (hazard ratio [HR] 4.67, 95% confidence interval [CI] 2.15 to 10.16, p <0.001). The ECG-CD group exhibited a higher risk of heart failure hospitalization (non-ECG-CD: 25%, ECG-CD: 29%, log-rank p = 0.01), but not mortality (non-ECG-CD: 50%, ECG-CD: 46%, log-rank p = 0.60) at 5-year follow-up. In conclusion, the ECG remained unchanged in most TAVI recipients without new postprocedural CD. Pre-existing ECG-CD was associated with an increased risk of PPM and heart failure hospitalization at long-term follow-up. These results provide reassuring data in the era of TAVI expanding toward candidates with a longer life expectancy, and highlight the importance of a closer follow-up of those patients with pre-existing ECG-CDs.

One-Year Follow-Up of Conduction Abnormalities After Transcatheter Aortic Valve Implantation With the SAPIEN 3 Valve

Long-term evolution of new-onset conduction abnormalities and need of permanent pacemaker implantation (PPI) after transcatheter aortic valve implantation (TAVI) have not been extensively evaluated. We describe the incidence and time course of new conduction abnormalities and the rate of PPI with the new-generation transcatheter aortic valve prosthesis Edwards SAPIEN 3 (S3). In total, 266 patients with severe aortic stenosis who underwent TAVI were retrospectively analyzed. Twelve-lead electrocardiograms at baseline, after TAVI, at discharge, at 1-, 6-, and 12-month follow-up were evaluated to identify conduction abnormalities and PPI requirements to investigate the correlates of PPI. After TAVI, a significant increase in PR interval duration and in QRS complex width was observed. New-onset left bundle branch block was observed in 65 patients (24%) after TAVI. The number of patients with left bundle branch block was maximum at hospital discharge and decreased at 12-month follow-up (39% and 32%, respectively). Thirty-five patients (13%) required PPI during the follow-up. However, paced rhythm was only observed in 7% of the patients with a complete 12-month follow-up. Patients who underwent PPI had a higher prevalence of first-degree atrioventricular block, complete right bundle branch block, and wider QRS complex at baseline. Baseline right bundle branch block and QRS width immediately after TAVI were the only variables independently associated with PPI. In conclusion, conduction disorders have a temporary nature after TAVI and showed a trend toward stabilization during the following months. With this new-generation device, the incidence of new conduction abnormalities requiring PPI is relatively low.

Bradyarrhythmia development and permanent pacemaker implantation after cardiac surgery

OBJECTIVE:

Bradyarrhythmia is one of the complications that may develop after cardiac surgery. Only a few studies have previously dealt with this concern, and in our study, we investigated the factors affecting the development of atrioventricular block or sinus node dysfunction and the requirement of permanent pacemaker following cardiac surgery.

METHODS:

A total of 62 patients who developed the atrioventricular (AV) block or sinus node dysfunction and required a permanent pacemaker following cardiac surgery were included in the study. Among these, 31 patients were evaluated prospectively, and the information regarding 31 patients was evaluated retrospectively based on hospital records. Demographic, clinical, and surgical information was recorded. Patients were grouped according to the types of procedures, including the coronary artery bypass graft, valve surgery, congenital heart disease, and combinations of these. Patients were evaluated by standard 12-lead electrocardiogram and transthoracic echocardiography preoperatively. The postoperative development of bradyarrhythmia and requirement of permanent pacemaker were evaluated.

RESULTS:

The mean age of patients with preoperative conduction abnormality and wide QRS was statistically significantly higher than those without these disorders. The odds ratio for preoperative conduction abnormality risk in patients over 70 years of age was found as 4.429 (95% confidence interval, 1.40–13.93). There was no gender-related statistically significant difference in terms of left ventricular ejection fraction, left ventricular dilatation, interventricular septum thickness, the time interval from operation to the development of AV block, concomitant diseases, and complication rates.

CONCLUSION:

Preoperative conduction abnormality and wide QRS in patients over 70 years of age was determined as a risk factor.

Clinical and Echocardiographic Outcomes Following Permanent Pacemaker Implantation After Transcatheter Aortic Valve Replacement: Meta-Analysis and Meta-Regression

BACKGROUND

Transcatheter aortic valve replacement has become the procedure of choice for inoperable, high-risk, and many intermediate-risk patients with aortic stenosis. Conduction abnormalities are a common finding after transcatheter aortic valve replacement and often result in permanent pacemaker (PPM) implantation. Data pertaining to the clinical impact of PPM implantation are controversial. We used meta-analysis techniques to summarize the effect of PPM implantation on clinical and echocardiographic outcomes after transcatheter aortic valve replacement.

METHODS AND RESULTS

Data were summarized as Mantel-Haenszel relative risk (RR) and 95% confidence intervals (CIs) for dichotomous variables and as standardized mean difference and 95% CI for continuous variables We used the Higgins I² statistic to evaluate heterogeneity. We found that patients with and without PPM have similar all-cause mortality (RR, 0.85; 95% CI, 0.70-1.03), cardiovascular mortality (RR, 0.84; 95% CI, 0.59-1.18), myocardial infarction (RR, 0.47; 95% CI, 0.20-1.11), and stroke (RR, 1.26; 95% CI, 0.70-2.26) at 30 days. The groups were also comparable in all-cause mortality (RR, 1.03; 95% CI, 0.92-1.16), cardiovascular mortality (RR, 0.69; 95% CI, 0.39-1.24), myocardial infarction (RR, 0.58; 95% CI, 0.30-1.13), and stroke (RR, 0.70; 95% CI, 0.47-1.04) at 1 year. We observed that the improvement in left ventricular ejection fraction was significantly greater in the patients without PPM (standardized mean difference, 0.22; 95% CI, 0.12-0.32).

CONCLUSIONS

PPM implantation is not associated with increased risk of all-cause mortality, cardiovascular mortality, stroke, or myocardial infarction both at short- and long-term follow-up. However, PPM is associated with impaired left ventricular ejection fraction recovery post-transcatheter aortic valve replacement.

Conduction abnormalities after transcatheter aortic valve implantation

In the last few years, transcatheter aortic valve implantation (TAVI) has become an alternative procedure in patients with severe aortic stenosis and high risk for surgical aortic replacement. Due to the anatomic correlation between aortic valve structure and conduction system of the heart, one of the most common complications after TAVI is conduction system disturbances which including bundle branch block, complete heart block and need for permanent pacemaker implantation. Although these disturbances are usually not lethal, they may have a great influence on patients' state and long term-survival. Several risk factors for conduction disturbances have been identified which including age, anatomy of the heart, periprocedural factors, type of implanted valve, preexisting abnormalities and comorbidities. As this technique becomes more familiar to physicians, patients should be carefully screened for risk factors for the development of conduction abnormalities after TAVI in order to provide effective prevention and proper treatment.

Incidence, indications and predicting factors of permanent pacemaker implantation after transcatheter aortic valve implantation: A retrospective study

BACKGROUND

As the number of transcatheter aortic valve implantation (TAVI) procedures is constantly increasing, it is important to consider common complications, such as pacemaker (PM) implantation, and their specific risk factors.

AIMS

Echocardiographic, computed tomography and electrocardiographic data were analysed to determine the predicting factors, if any, associated with PM implantation.

METHODS

This retrospective study included patients referred to Nancy University Hospital for a TAVI procedure from January 2013 to December 2015. Both Medtronic CoreValve and Edwards SAPIEN valves were implanted. Patients with preprocedurally implanted PMs and/or referred from another institution were excluded.

RESULTS

Of 208 TAVI patients, 23 had a pre-existing PM and were excluded. A new PM was required in 38 patients (20.5%). Pre-existing right bundle branch block (RBBB), the use of the Medtronic CoreValve and large prostheses were identified as predictors of PM implantation (P=0.0361, P=0.0004 and P=0.0019, respectively). Using logistic regression, predictors of PM implantation included first-degree atrioventricular block (odds ratio 3.7, 95% confidence interval 1.5-9.1; P=0.0054) and large aortic annulus diameter in echocardiography (odds ratio 1.2, 95% confidence interval 1-1.4; P=0.0447), with a threshold of 24.1mm. For the combination of preTAVI PR duration >220ms and QRS duration >120ms, the positive predictive value for PM implantation reached 80%.

CONCLUSION

Use of the Medtronic CoreValve, RBBB and first-degree atrioventricular block are major risk factors for post-TAVI PM implantation. In addition, large aortic annulus and large valvular prosthesis are independent risk factors for PM implantation. The combination of preTAVI prolonged PR interval and increased QRS duration could be used as a marker for periprocedural PM implantation.

Differences in cardiovascular risk profile between electrocardiographic hypertrophy versus strain in asymptomatic patients with aortic stenosis (from SEAS data)

Electrocardiograms are routinely obtained in clinical follow-up of patients with asymptomatic aortic stenosis (AS). The association with aortic valve, left ventricular (LV) response to long-term pressure load, and clinical covariates is unclear and the clinical value is thus uncertain. Data from clinical examination, electrocardiogram, and echocardiogram in 1,563 patients in the Simvastatin and Ezetimibe in Aortic Stenosis (SEAS) study were used. Electrocardiograms were Minnesota coded for arrhythmias and atrioventricular and intraventricular blocks; LV hypertrophy was assessed by Sokolow-Lyon voltage and Cornell voltage-duration criteria; and strain by T-wave inversion and ST-segment depression. Degree of AS severity was evaluated by echocardiography as peak aortic jet velocity and LV mass was indexed by body surface area. After adjustment for age, gender, LV mass index, heart rate, systolic and diastolic blood pressures, blood glucose, digoxin, antiarrhythmic drugs, drugs acting on the renin-angiotensin system, diuretics, β blockers and calcium receptor blockers; peak aortic jet velocity was significantly greater in patients with electrocardiographic strain (mean difference 0.13 m/s, p <0.001) and LV hypertrophy by Sokolow-Lyon voltage criteria (mean difference 0.12 m/s, p = 0.004). After similar adjustment, LV mass index was significantly greater in patients with electrocardiographic strain (mean difference 14.8 g/cm(2), p <0.001) and LV hypertrophy by Sokolow-Lyon voltage criteria and Cornell voltage-duration criteria (mean differences 8.8 and 17.8 g/cm(2), respectively, p <0.001 for the 2 comparisons). In multiple comparisons patients with electrocardiographic strain had increased peak aortic jet velocity, blood glucose, and uric acid, whereas patients with LV hypertrophy by Sokolow-Lyon voltage criteria were younger and patients with LV hypertrophy by Cornell voltage-duration criteria more often were women. In conclusion, electrocardiographic criteria for LV hypertrophy and strain are independently associated with peak aortic jet velocity and LV mass index. Moreover, clinical covariates differ significantly between patients with electrocardiographic strain and those with LV hypertrophy by Sokolow-Lyon voltage criteria and Cornell voltage-duration criteria.

Early and persistent intraventricular conduction abnormalities and requirements for pacemaking after percutaneous replacement of the aortic valve

OBJECTIVES

In this retrospective study, we examined the incidence of post-procedural conduction abnormalities and the need for pacing in patients undergoing percutaneous implantation of the aortic valve.

BACKGROUND

Safety and feasibility studies have suggested anecdotally the occurrence of conduction abnormalities and requirements for pacing after percutaneous implantation of the aortic valve.

METHODS

We examined the standard 12-lead electrocardiograms (ECGs) of 40 consecutive patients in whom a CoreValve Revalving System (CoreValve, Paris, France) was implanted between November 2005 and March 2008. We examined the 12-lead ECG before treatment, after treatment, and at 1-month follow-up. We documented the requirements for temporary or permanent pacemaking.

RESULTS

The mean age of patients was 82 +/- 7 years. Post-procedural mortality at 72 h was 0%. There was a significant increase in the frequency of left bundle branch block (LBBB) after percutaneous aortic valve replacement (15% before treatment vs. 55% after treatment, p = 0.001). Although the incidence of LBBB had decreased after follow-up of 1 month, it did not reach statistical significance, with the proportion decreasing from 55% to 48% (p = 0.63). The only 2 patients with pre-treatment right bundle branch block became dependent on temporary pacing immediately after valve implantation and subsequently needed permanent pacing. A temporary and permanent pacemaker was required in 20% and 18% of patients, respectively.

CONCLUSIONS

In this study, there was a significant increase in the frequency of LBBB after percutaneous insertion of the aortic valvar prosthesis. Patients with pre-existing right bundle branch block may be at risk for the development of complete heart block and subsequent need for pacing.

Atrioventricular conduction abnormalities in patients undergoing isolated aortic or mitral valve replacement

Cardiac conduction defects are common in patients with aortic valve disease. Several studies have suggested that the spontaneous occurrence of complete heart block in these patients is related to the extent of calcium deposits in the aortic valve and adjacent structures. No studies have been done to relate the occurrence of complete heart block at the time of valve replacement to predictive factors. We evaluated 102 consecutive patients undergoing isolated aortic valve replacement and 100 patients undergoing isolated mitral valve replacement. Although transient complete heart block was relatively common in each group (17.6% and 13%, respectively), we were not able to identify any factors predictive of its occurrence. There was a very low incidence of late heart block in a follow-up period of over four years. Thus, the capability for temporary pacing is mandatory in patients undergoing valve replacement. However, transient complete AV block during the perioperative period does not predict late recurrence of AV block and, therefore, prophylactic pacemaker or electrode implantation during or following transient block appears unnecessary.

Electrocardiographic observations in severe aortic valve stenosis: correlative necropsy study to clinical, hemodynamic,, and ECG variables demonstrating relation of 12-lead QRS amplitude to peak systolic transaortic pressure gradient

Most ECG studies in patients with aortic valve stenosis (AS) have involved living patients in whom the status of the left ventricular (LV) myocardium, epicardial coronary arteries, and mitral valve was not precisely known. We examined the 12-lead ECG recorded within 2 months of death in 50 patients aged 16 to 65 years (mean 48) with peak systolic pressure gradients (PSPG) across the aortic valve ranging from 52 to 180 mm Hg (mean 98) and anatomically normal mitral valves. Excluding four patients with complete left bundle branch block (LBBB), 44 (96%) of the other 46 patients had the usual voltage criteria for LV hypertrophy (LVH). Measurement of the total 12-lead QRS amplitude, which ranged from 144 to 417 mm (10 mm = 1 mV), (mean 257) proved useful for it correlated directly with PSPG across the aortic valve and, when the four LBBB patients were excluded, with the peak LV systolic pressure. The total 12-lead QRS amplitude (mm) was similar in most patients to the LV systolic pressure (mm Hg). Thus, subtraction of the indirect systemic arterial systolic pressure (mm Hg) from the total 12-lead QRS amplitude (mm) provides a reasonable noninvasive prediction of the PSPG across the aortic valve in patients with moderate to severe AS. Additionally, the mean of the total 12-lead QRS amplitude was significantly (p less than 0.05) greater in the 11 younger (less than or equal to 40 years) than in the 39 older patients (278 mm vs 257 mm), in the 14 women than in the 36 men (277 mm vs 240 mm), in the 22 patients with heavier (greater than 600 gm) hearts (274 mm vs 244 mm), in the 34 patients without compared to the 16 with significant coronary arterial narrowing (270 mm vs 238 mm), and in the 22 patients without compared to the 24 with ECG myocardial damage patterns (269 mm vs 236 mm).

Natural history of chronic second-degree atrioventricular nodal block

This report details our experience with documented chronic second-degree atrioventricular (AV) nodal block (proximal to His [H]) in 56 patients. Forty-six men (82%) and 10 women (18%), ages 18-87 years, were studied. Nineteen of the patients (34%) had no organic heart disease (including seven trained athletes) and 37 (66%) had organic heart disease. ECGs in all patients demonstrated episodes of type I second-degree block; five patients also had periods of 2:1 block. Prospective follow-up patients with no organic heart disease (157-2280 days, mean 1395 +/- 636 days) revealed one patient with clear indication for permanent pacing because of bradyarrhythmic symptoms (permanently placed on day 220 of follow-up). Two patients died nonsuddenly. In patients with organic heart disease (prospective follow-up of 60-2950 days, mean 1347 +/- 825 days), pacemakers were implanted in 10 patients, primarily for treatment of congestive heart failure in eight and syncope in two. Sixteen patients died -- three suddenly, seven with congestive heart failure, two of an acute myocardial infarction and four of causes unrelated to cardiac disease. In summary, chronic second-degree AV nodal block has a relatively benign course in patients without organic heart disease. In patients with organic heart disease, prognosis is poor and related to the severity of underlying heart disease.