A pragmatic approach for mortality prediction after surgery in infective endocarditis: optimizing and refining EuroSCORE

OBJECTIVE

To simplify and optimize the ability of EuroSCORE I and II to predict early mortality after surgery for infective endocarditis (IE).

METHODS

Multicentre retrospective study (n = 775). Simplified scores, eliminating irrelevant variables, and new specific scores, adding specific IE variables, were created. The performance of the original, recalibrated and specific EuroSCOREs was assessed by Brier score, C-statistic and calibration plot in bootstrap samples. The Net Reclassification Index was quantified.

RESULTS

Recalibrated scores including age, previous cardiac surgery, critical preoperative state, New York Heart Association >I, and emergent surgery (EuroSCORE I and II); renal failure and pulmonary hypertension (EuroSCORE I); and urgent surgery (EuroSCORE II) performed better than the original EuroSCOREs (Brier original and recalibrated: EuroSCORE I: 0.1770 and 0.1667; EuroSCORE II: 0.2307 and 0.1680). Performance improved with the addition of fistula, staphylococci and mitral location (EuroSCORE I and II) (Brier specific: EuroSCORE I 0.1587, EuroSCORE II 0.1592). Discrimination improved in specific models (C-statistic original, recalibrated and specific: EuroSCORE I: 0.7340, 0.7471 and 0.7728; EuroSCORE II: 0.7442, 0.7423 and 0.7700). Calibration improved in both EuroSCORE I models (intercept 0.295, slope 0.829 (original); intercept -0.094, slope 0.888 (recalibrated); intercept -0.059, slope 0.925 (specific)) but only in specific EuroSCORE II model (intercept 2.554, slope 1.114 (original); intercept -0.260, slope 0.703 (recalibrated); intercept -0.053, slope 0.930 (specific)). Net Reclassification Index was 5.1% and 20.3% for the specific EuroSCORE I and II.

CONCLUSIONS

The use of simplified EuroSCORE I and EuroSCORE II models in IE with the addition of specific variables may lead to simpler and more accurate models.

International experts' practice in the antibiotic therapy of infective endocarditis is not following the guidelines

OBJECTIVE

The management of infective endocarditis (IE) may differ from international guidelines, even in reference centres. This is probably because most recommendations are not based on hard evidence, so the consensus obtained for the guidelines does not represent actual practices. For this reason, we aimed to evaluate this question in the particular field of antibiotic therapy.

METHODS

Thirteen international centres specialized in the management of IE were selected, according to their reputation, clinical results, original research publications and quotations. They were asked to detail their actual practice in terms of IE antibiotic treatment in various bacteriological and clinical situations. They were also asked to declare their IE-related in-hospital mortality for the year 2015.

RESULTS

The global compliance with guidelines concerning antibiotic therapy was 58%, revealing the differences between theoretical 'consensus', local recommendations and actual practice. Some conflicts of interest were also probably expressed. The adherence to guidelines was 100% when the protocol was simple, and decreased with the seriousness of the situation (Staphylococus spp. 54%-62%) or in blood-culture-negative endocarditis (0%-15%) that requires adaptation to clinical and epidemiological data.

CONCLUSION

Worldwide experts in IE management, although the majority of them were involved and co-signed the guidelines, do not follow international consensus guidelines on the particular point of the use of antibiotics.

Immediate and long-term outcome of left-sided infective endocarditis. A 12-year prospective study from a contemporary cohort in a referral hospital

The aim of this study was to describe the immediate and long-term prognosis of a contemporary cohort of patients with left-sided infective endocarditis (LSIE). A prospective observational cohort study was conducted in a referral centre. Between January 2000 and December 2011, all consecutive adult patients with LSIE were followed-up until death, relapse, recurrence, need for late surgery, or last control. During the active phase of IE, 174 of 438 patients underwent surgery (40% overall; 43% native valve (NVIE), 30% prosthetic valve (PVIE)) and 125 died (29% overall; 26% NVIE, 39% PVIE). The median follow-up in survivors was 3.2 years (interquartile range (IQR) 1.0-6.0 years). Relapses occurred in seven patients (2.2%; 95% CI, 1.1-4.5) and recurrences in eight (2.6%; 95% CI, 1.3-5.0), with an incidence density of 0.0067 per patient-year (95% CI, 0.0029-0.0133) and high mortality (75% of recurrences). Only four of 130 survivors (3.1%; 95% CI, 1.2-7.6) who were treated surgically during the active phase of the disease, and 14/183 (7.7%; 95% CI, 4.6-12.4) of those not undergoing surgery needed operation during follow-up (p 0.09). In the 313 survivors, actuarial survival was 86% at 1 year (87% NVIE, 83% PVIE), 79% at 2 years (81% NVIE, 72% PVIE) and 68% at 5 years (71% NVIE, 57% PVIE). At 1 year, 115 of 397 patients (29.0%; 95% CI, 24.7-33.6) remained alive, with no surgery requirement, relapse or recurrence. LSIE is associated with considerable in-hospital and long-term mortality, especially PVIE. However, relapses, recurrences and the need for late surgery are uncommon.

Candida infective endocarditis

Candida infective endocarditis (IE) is uncommon but often fatal. Most epidemiologic data are derived from small case series or case reports. This study was conducted to explore the epidemiology, treatment patterns, and outcomes of patients with Candida IE. We compared 33 Candida IE cases to 2,716 patients with non-fungal IE in the International Collaboration on Endocarditis-Prospective Cohort Study (ICE-PCS). Patients were enrolled and the data collected from June 2000 until August 2005. We noted that patients with Candida IE were more likely to have prosthetic valves (p < 0.001), short-term indwelling catheters (p < 0.0001), and have healthcare-associated infections (p < 0.001). The reasons for surgery differed between the two groups: myocardial abscess (46.7% vs. 22.2%, p = 0.026) and persistent positive blood cultures (33.3% vs. 9.9%, p = 0.003) were more common among those with Candida IE. Mortality at discharge was higher in patients with Candida IE (30.3%) when compared to non-fungal cases (17%, p = 0.046). Among Candida patients, mortality was similar in patients who received combination surgical and antifungal therapy versus antifungal therapy alone (33.3% vs. 27.8%, p = 0.26). New antifungal drugs, particularly echinocandins, were used frequently. These multi-center data suggest distinct epidemiologic features of Candida IE when compared to non-fungal cases. Indications for surgical intervention are different and mortality is increased. Newer antifungal treatment options are increasingly used. Large, multi-center studies are needed to help better define Candida IE.

Enoxaparin as bridging anticoagulant treatment in cardiac surgery

OBJECTIVE

To assess enoxaparin as bridging anticoagulant treatment in cardiac surgery.

METHODS

Prospective registry of those patients who underwent cardiac surgery in our centre between December 2003 and June 2004 and required long-term anticoagulation. Subcutaneous enoxaparin was used as bridging anticoagulant treatment according to a pre-established protocol. The global thromboembolic risk was carefully assessed in all patients. All patients were followed up for 3 months.

RESULTS

Of 140 patients who were included (mean (SD) age 66 (11); 49% female), 51 were already receiving long-term acenocumarol treatment before the index intervention. 50% of the patients were at high or very high risk for thromboembolic events in the postoperative period. The mean (SD) number of days between surgery and the first dose of anticoagulant was 2.01 (7) for acenocumarol and 1 (1.01) for enoxaparin. The mean (SD) daily dose of enoxaparin was 1.1 (0.27) mg/kg. Six thromboembolic events (4.3%; 95% CI 1.6 to 9.1) occurred, but only four of them were plausibly related to enoxaparin (2.9%; 95% CI 0.8 to 7.1). Six major haemorrhagic events (4.3%; 95% CI 1.6 to 9.1) occurred, but only three were plausibly related to enoxaparin (2.1%; 95% CI 0.4 to 6.1).

CONCLUSIONS

These findings show a reasonable rate of adverse events using enoxaparin as bridging anticoagulant treatment in cardiac surgery. Randomised studies are necessary to evaluate the real efficacy and safety of enoxaparin as bridging anticoagulant treatment in cardiac surgery.

Experience with enoxaparin in patients with mechanical heart valves who must withhold acenocumarol

OBJECTIVES

To evaluate the incidence of thromboembolic and haemorrhagic events in a cohort of patients with mechanical heart valves who had to withhold acenocumarol and were treated with enoxaparin.

DESIGN

Observational prospective study.

SETTING

In hospital; after discharge, and follow up by telephone call.

PATIENTS AND METHODS

All consecutive patients with mechanical heart valves admitted to the authors' hospital between May 1999 and January 2002 who had to interrupt treatment with acenocumarol and were treated with enoxaparin as an alternative to other methods were enrolled. In each patient, the following characteristics were prospectively determined: the reason for interrupting acenocumarol, demographic data, estimated global risk for thromboembolic events, international normalised ratio before starting enoxaparin treatment, number of days taking enoxaparin, and mean level of anti-Xa activity during treatment. All patients were followed up through clinical history during the hospitalisation and by telephone after discharge to detect thromboembolic events.

MAIN OUTCOME MEASURE

Presence of thromboembolic or haemorrhagic events.

RESULTS

82 patients were identified and followed up for a mean of 2.8 months (range 1.5-3.5 months) after discharge. 61 of them (74%) had one or more associated thromboembolic risk factors. Acenocumarol was interrupted (to perform an invasive procedure in 74 patients and because of haemorrhagic complication in 8) an average of 11.2 days (range 3-40 days). Most patients received the standard enoxaparin dose (1 mg/kg at 12 hour intervals). Mean (SD) anti-Xa activity was 0.58 (0.3) IU/ml (median 0.51). There were 8 minor and 1 major bleeding events during enoxaparin treatment. No thromboembolic complications were clinically detected during hospitalisation or during follow up (95% confidence interval 0% to 3.6%).

CONCLUSIONS

Enoxaparin may be an effective and relatively safe substitute anticoagulant for patients with mechanical heart valves who must withhold acenocumarol.

[New aspects in aortic valve disease]

Renewed interest for aortic valve disease has evolved in recent years. Aortic valve replacement has become the second most frequent cause of cardiac surgery, following coronary bypass surgery. In addition, the etiologic and physiopathologic knowledge of this disorder has improved. In the present paper we analyze three aspects of the disease which are, at present, the subject of study and controversy: first, we discuss the possible relationship between degenerative aortic stenosis and atherosclerosis; second, the involvement of the aortic root in cases of bicuspid aortic valve; and third, the surgical indications in asymptomatic patients with either aortic stenosis or regurgitation.

[Practice guidelines of the Spanish Society of Cardiology on endocarditis]

Infectious endocarditis is a disease which mainly involves the cardiac valves. It has a bad prognosis and is caused by a great variety of microorganisms. Prophylaxis is important although the effectiveness and the best way to achieve it remain unclear. Recommendations are herein presented. The diagnosis is based on clinical, bacteriological, and echocardiographic findings mainly based on Duke's criteria. Transthoracic and transesophageal echography are not only of diagnostic value but are also a tool to determine the therapy to follow. Antibiotic therapy should be selected according to the organisms isolated and their in vitro susceptibility. Guidelines for empirical antibiotic therapy in cases of negative cultures are also included. Lastly, indications and time for surgery are discussed.

Strategy for optimal aortic regurgitation quantification by Doppler echocardiography: agreement among different methods

BACKGROUND

Although different Doppler methods have been validated for aortic regurgitation quantification, the benefit of combining information from different methods has not been defined.

METHODS

Our study included 2 phases. In the initial phase (60 patients), Doppler parameters (jet width, short-axis jet area, apical jet area, regurgitant fraction from pulmonary and mitral flow, and deceleration slope) were correlated with angiography; range values for each severity grade were defined and intraobserver and interobserver and intermachine variability were studied. In the validation phase (158 patients), defined value ranges were prospectively tested and a strategy based on considering as the definitive severity grade that in which the two best methods agreed was tested.

RESULTS

Jet width had the best correlation with angiography (r = 0.91), and its ratio with the left ventricular outflow diameter did not improve the correlation (r = 0.85) and decreased reproducibility. Apical jet area and regurgitant fraction from pulmonary flow permitted acceptable quantification (r = 0.87 and 0.86, respectively) but with worse reproducibility. The other methods were not assessable in 20% to 30% of studies. Concordance with angiography decreased in jet width when the jet was eccentric (90% vs 77%, P <.01), in apical jet area when mitral valve disease was present (84% vs 65%, P <.02), and in short-axis jet area and regurgitant fraction from pulmonary flow with concomitant aortic stenosis (77% vs 44%, P <.002 and 77% vs 53%, P <.02, respectively). Agreement with angiography was very high (94 [95%] of 99) when severity grade coincided in both jet width and apical jet area. In 59 cases without concordance, regurgitant fraction from pulmonary flow was used as a third method. Overall, this strategy permitted concordance with angiography in 146 patients (92%).

CONCLUSIONS

Jet width is the best predictor in aortic regurgitation quantification by Doppler echocardiography. However, better results were obtained when a strategy based on concordance between jet width and another Doppler method was established, particularly when the jet was eccentric.

Infective endocarditis due to Staphylococcus aureus: deleterious effect of anticoagulant therapy

BACKGROUND

The use of anticoagulant therapy in patients with infective endocarditis (IE) is a controversial issue.

OBJECTIVE

To study the impact of anticoagulant therapy on the clinical outcome, mortality, and cause of death in a series of patients with native and prosthetic left-sided Staphylococcus aureus IE.

METHODS

This report is based on all consecutive cases of IE diagnosed at our hospital between 1975 to 1997. Clinical data, including the use of anticoagulant therapy at the time of diagnosis, were prospectively obtained, and antibiotic treatment and surgical indications were uniform throughout the study period. Computed tomographic scans of all clinical records were reviewed.

RESULTS

Of 637 consecutive patients with IE, 56 had left-sided S aureus IE affecting native valves in 35 patients and prosthetic valves in 21 patients. Of the patients with prosthetic valve IE, 19 (90%) were taking oral anticoagulant therapy at the time of diagnosis while no patient with native valve IE was receiving such treatment. There were no differences between native valve IE and prosthetic valve IE in age, sex, embolic episodes, and number of central nervous system complications. Mortality was higher in prosthetic valve IE than in native valve IE (71% vs 37%; P=.02). No patient with native valve IE died due to central nervous system complications, while 73% (11 of 15 patients) with prosthetic valve IE died due to central nervous system complications. The difference in the distribution of the type of death (stroke vs other) was significant (P<.007).

CONCLUSIONS

Our results suggest that in left-sided S aureus IE anticoagulant therapy is closely associated with death due to neurologic damage. According to our data, as soon as the clinical diagnosis of S aureus IE is indicated the use of anticoagulant therapy should be immediately stopped until the septic phase of the disease is overcome.

Clinical outcome and long-term prognosis of late prosthetic valve endocarditis: a 20-year experience

A prospective study of the clinical characteristics and evolutionary patterns of 59 cases of late prosthetic valve endocarditis (LPVE) that occurred between January 1975 and December 1994 was performed. Of these 59 cases of LPVE, 48 involved mechanical valves and 11 involved biological valves. Etiologies were as follows: streptococci, 41% of cases; staphylococci, 25%; enterococci, 13%; and miscellaneous, 21%. Echocardiography documented vegetations in 21 patients, paravalvular abscesses in 10, and prosthetic leaks in 34. Emboli occurred in 22 patients, and heart failure in 19 patients. Forty-two patients received medical treatment alone, and 17 received medical treatment and underwent valve replacement surgery. The in-hospital mortality rate was 25%; staphylococcal infection caused 67% of deaths, streptococcal infection caused 5%, and other etiologies caused 23% (P = .0004). After adjustment for age and type of prosthesis, multiple logistic regression revealed an odds ratio for death due to nonstreptococcal infections of 9.67. The overall survival rate was 59% at 5 years and 52% at 10 years. During follow-up, 17 patients needed new valves. At the end of follow-up, only 13 patients remained alive and had the same prosthesis that they had at the time of the diagnosis of LPVE.

Previous aspirin use may attenuate the severity of the manifestation of acute ischemic syndromes

BACKGROUND

The present study was designed to investigate whether the prior use of aspirin could influence the severity of the manifestation of acute coronary artery syndromes, given the well-documented observations that aspirin can prevent myocardial infarction, stroke, and death in cardiovascular disease.

METHODS AND RESULTS

A series of 539 consecutive patients admitted to the Coronary Care Unit of a General Hospital was carefully characterized in a study with an ambidirectional design, with regard to previous medical history, aspirin use, and subsequent hospital diagnosis. Among the 214 patients previously taking aspirin, the hospital diagnosis was myocardial infarction in 24% and unstable angina in 76% compared with 54% and 46%, respectively, among the 325 not taking aspirin (P < .0001), for a reduction in the odds ratio of myocardial infarction with aspirin of 72% (95% CI, 59% to 90%). The decrease in odds was homogeneous in all subsets studied and independent of age, sex, previous angina, or previous myocardial infarction. The myocardial infarction was of a Q-wave type in 62% of aspirin users compared with 76% of nonusers (P < .05). By multivariate analysis, previous aspirin use was a strong predictor of unstable angina versus myocardial infarction and the only independent predictor of non-Q-wave versus Q-wave myocardial infarction.

CONCLUSIONS

This study, thus, suggests a shift to less severe manifestation of acute coronary syndromes with aspirin use, implying that the failure of the drug in many patients with an acute coronary syndrome is only partial and that aspirin has the potential of attenuating the severity of the underlying acute thrombotic disease process.

Ventricular arrhythmias in aortic valve disease: a further marker of impaired left ventricular function

One hundred and twenty stable patients with pure and severe aortic valve disease and without coronary lesions (aortic stenosis, 43 patients; aortic regurgitation, 45 patients; combined aortic stenosis and regurgitation, 32 patients) who had been submitted to haemodynamic studies were prospectively studied with standard electrocardiograms, M-mode echocardiograms, and 24-hour ambulatory electrocardiography (Holter recording). The frequency and complexity of ventricular arrhythmias were related to clinical parameters such as functional class, type of lesion and presence of syncope, and to parameters of left ventricular hypertrophy and function. Ventricular arrhythmias were present in 92% of patients. A high number of ventricular premature beats was directly correlated with parameters of complexity of the arrhythmia. A significant relation was found between electrocardiographic left ventricular hypertrophy and Ryan class (P less than 0.05), and an inverse relation between maximal number of ventricular premature beats in any hour and left ventricular ejection fraction (P less than 0.05). The group of patients with aortic regurgitation showed a higher total number of ventricular premature beats per 24 hours (P less than 0.001), a higher maximal number of these in any hour (P less than 0.01), a higher number of patients with pairs (P less than 0.001), and a higher number of patients in Ryan classes 3, 4A, 4B (P less than 0.01). This study shows a high incidence of ventricular arrhythmias in aortic valve disease, and especially in aortic regurgitation, with a significant relation between left ventricular hypertrophy and function, and number and complexity of arrhythmias.

Late prosthetic valve endocarditis. Immediate and long-term prognosis

From 1975 to 1989, 307 consecutive episodes of infective endocarditis were diagnosed in our hospital. Of those, 35 were cases of late prosthetic valve endocarditis, defined as those occurring after 12 months of valvular replacement. Blood cultures grew streptococci in 15 patients (43 percent), staphylococci in seven (20 percent), enterococci in five (14 percent), Gram-negative bacilli of HACEK group in four (11.5 percent), and Candida in one. Blood cultures were negative in three cases (prosthetic infection was confirmed at surgery). Heart failure due to prosthetic dysfunction occurred in seven patients (20 percent) and emboli in 12 (34 percent). Early valvular replacement was performed in six patients (17 percent). Complications and mortality were dependent on the infective agent. Overall mortality was 23 percent, no death occurred from streptococcal infection, whereas mortality with endocarditis by organisms of the HACEK group and Staphylococcus was 50 percent and 43 percent, respectively. During a mean follow-up of five years, 11 patients (those with prosthetic leaks diagnosed during the active infection and patients with biologic prostheses) required surgery. There was one relapse in a patient with staphylococcal endocarditis and one recurrence, six years after the initial episode. We conclude that immediate prognosis of late prosthetic valve endocarditis depends on the infective agent. Although the immediate prognosis of streptococcal infections is good, the need for early reoperation during follow-up due to progressive perivalvular leak is high. Also, it appears that deterioration of bioprostheses proceeds swiftly after the cure of infection.

[Infectious endocarditis in drug addicts: a study of 71 cases]

Infective endocarditis (IE) is a severe and relatively common condition in parenteral drug abusers (PDA). Seventy-one IE episodes in 59 PDAs admitted to the Hospital General Vall d'Hebron from August 1978 to December 1988 were evaluated. The disease basically involved young males, with a progressively increasing incidence throughout the decade and a higher frequency during August. Fever was a constant symptom, with a duration of less than 10 days before admission in 73% of cases. Staphylococcus aureus was the most common pathogen (85% of episodes). Vegetations were detected by echocardiography in 70% of cases. In 82% of episodes the right side of the heart was involved, particularly the tricuspid valve. The initial chest X-ray film was abnormal in 57.5% of episodes. In 7 patients features of heart failure were present at admission; most had left heart endocarditis. Three patients with left heart endocarditis required surgical therapy. Overall mortality was 13%; it was 6% in patients with only tricuspid involvement and 27% when the left heart was involved.

[Apical hypertrophic myocardiopathy: differential diagnosis with ischemic cardiopathy]

A 53-year-old patient was admitted to our hospital because of exertional angina and electrocardiographic changes suggesting ischemic heart disease. The echocardiogram and cardiac catheterization demonstrated apical hypertrophic cardiomyopathy with normal coronary angiogram. We review the clinical features, treatment and prognosis of this condition. We insist on the importance of clinically suspecting it in any asymptomatic patient, or with any type of cardiac symptoms, and giant negative T waves with electrocardiographic features of left ventricular hypertrophy.

[The ergonovine test: an episode of hallucinations]

The ergonovine maleate provocation test for the diagnosis of coronary spasm is widely used in patients with rest angina. A patient who developed an episode of psychotomimetic symptoms after the administration of intravenous ergonovine is presented. This side effect of ergonovine maleate had not been previously reported.

Appraisal of factors influencing the normal sinus node recovery time

The normal period of depression of sinoatrial node automaticity (sinus node recovery time, SNRT) following one minute of overdrive right atrial pacing was evaluated in 34 subjects, aged 27--83 years. Specific attention was paid to the influence of the patient's heart rate, atrial pacing rate (100 and 130 bpm) and site, and of vagal and sympathetic effects, as assessed by observations following the administration of atropine, 0 . 03 mg/kg, and propranolol, 0 . 15 mg/kg. Normal SNRT was 1046 +/- 17 ms at 100 bpm and 980 +/- 19 ms at 130 bpm. Linear regression analysis showed that at pacing rates of both 100 and 130 bpm, both before and after autonomic block, a highly significant relation existed between SNRT and the stable P-P interval observed after cessation of pacing. These regression equations were used to develop a correction factor for cycle length in assessing SNRT (corrected SNRT = SNRT--0 . 86 X cycle length, where 0 . 86 was the slope of the regression equation). The mean corrected SNRT was 314 +/- 10 ms and 290 +/- 8 ms at 100 and 130 bpm, respectively. Vagal influences increased SNRT and were of greater magnitude than the decrease in SNRT due to sympathetic effects. Corrected SNRT was significantly longer following left atrial than following right atrial pacing, but in those eight patients studied, was not significantly different following right atrial or right ventricular stimulation.

Atrial pacing in ventricular tachycardia and supraventricular tachycardia with aberrant intraventricular conduction: diagnostic and therapeutic implications

The diagnostic and potential therapeutic value of rapid right atrial pacing in ventricular tachycardia and supraventricular tachycardia with aberrant intraventricular conduction, was examined. The effect of right atrial pacing at incremental rates beginning 10 bpm above the rate of the tachycardia was studied in five patients with ventricular tachycardia, and in four patients with supraventricular tachycardia with rate-related bundle branch block aberration, the mechanism of tachycardia having been demonstrated at electrophysiology study. Atrial pacing resulted in persistent (four) or occasional (one) normalisation of the QRS complexes to that seen in sinus rhythm in those five patients with ventricular tachycardia. The intraventricular conduction pattern persisted with atrial pacing in those patients with supraventricular tachycardia and aberrant intraventricular conduction. This confirms that atrial pacing is a useful and simple diagnostic test in wide QRS tachycardia, which does not require sophisticated electrophysiological facilities. In three of the patients with ventricular tachycardia, atrial pacing terminated the arrhythmia, suggesting potential therapeutic use of rapid atrial pacing in such patients.

Sick sinus syndrome and AV node re-entry

A 69-year-old man presented with recurrent palpitations since childhood. Electrophysiology studies performed on two separate occasions revealed the combination of sick sinus syndrome and AV node re-entrant tachycardia. The case is reported because it illustrates marked temporal variability in the electrophysiological properties of the dual AV node pathways, and also deleterious effects of verapamil on sinoatrial node function.

Intermittent atrioventricular block: procainamide administration as a provocative test

Twelve patients with clinical features suggesting possible intermittent high degree atrioventricular block were studied. All 12 patients had basic 1:1 atrioventricular conduction but nine had an electrocardiographic pattern of bifascicular distal conduction disease (right bundle branch block with left anterior or posterior hemiblock, or left bundle branch block). Intracardiac conduction was assessed by recording of the His bundle electrocardiogram and atrial pacing techniques, before and 20 minutes after intravenous administration of procainamide, in a dose of up to 10 mg/kg. Before procainamide administration, seven of the 12 patients had a prolonged H-V interval (greater than 55 ms). Procainamide administration lengthened the H-V interval in all 12 patients by 5--40 ms. In five patients, procainamide induced second or third degree AV block below the level of the bundle of His. It was concluded that the administration of procainamide may be a useful provocative test of distal conduction in patients with possible intermittent AV block.