Stellate ganglion block for the management of electrical storm: An observational study

INTRODUCTION

Electrical storm is a life-threatening emergency with a high mortality rate. When acute conventional treatment is ineffective, stellate ganglion block can help control arrhythmia by providing a visceral cervicothoracic sympathetic block. The objective of this study is to assess the effectiveness and safety of stellate ganglion block in the management of refractory arrhythmic storm.

METHOD

Follow-up of a cohort of patients with refractory electrical storm that met the criteria for performing stellate ganglion block. The block was ultrasound-guided at C6 using local anaesthetic and a steroid - left unilateral first, bilateral if no response, followed by fluoroscopy-guided radiofrequency ablation at C7 if there was a favourable response but subsequent relapse.

RESULTS

Seven patients were included. The in-hospital mortality rate was 14.29%. Four patients received unilateral and 3 bilateral stellate ganglion block. Six were ablated and 1 received an implantable cardioverter-defibrillator. Electrical storm was controlled temporarily beyond the effect of the local anaesthetic in all patients. Three patients underwent radiofrequency ablation and 2 underwent surgical thoracic sympathectomy. The only side effect was Horner's syndrome, which was observed in all cases after administering a stellate ganglion block with local anaesthetic. Two patients died after discharge and 4 are alive at the time of writing, 3 of them have not been re-admitted for ventricular events for more than 2 years.

CONCLUSION

Ultrasound-guided stellate ganglion block is an effective and safe complement to standard cardiological treatment of refractory electrical storm.

The VR leadless pacemaker: Results of an expert panel using the RAND/UCLA method

BACKGROUND

Leadless pacemakers were developed to reduce complications associated with transvenous pacemaker implantation and long-term follow-up. Existing international guidelines lack detailed instructions on patients suitable for leadless pacemaker implantation. Our aim was to develop a consensus document that provides medical guidance for all health professionals involved in the indication and implantation of Transcatheter Pacing System single-chamber device (VR leadless) pacemakers for patients with atrial fibrillation or in sinus rhythm.

METHODS

A panel of experts, including interventional and non-interventional cardiologists, used the Research ANd Development/University of California at Los Angeles (RAND/UCLA) method to rate the appropriateness of leadless pacemaker implantation for 64 scenarios in patients with atrial fibrillation and 192 scenarios in sinus rhythm. The scenarios were rated individually and again during a moderated group session. Median ratings and level of agreement were calculated to classify each scenario as appropriate, inappropriate, or questionable.

RESULTS

This consensus statement, based on available literature and the experts' opinions, summarizes recommendations for standardizing and optimizing leadless pacemaker implantation. The limitation for vascular access via the superior vena cava was the most influential variable when indicating leadless pacemaker implantation in both patients with atrial fibrillation and patients in sinus rhythm.

CONCLUSIONS

Life expectancy, risk of infection, prosthetic valve, left ventricular ejection fraction (LVEF), limitation for vascular access via the superior vena cava, and mobility and exercise capacity determine who is advised to undergo VR leadless pacemaker implantation. More prospective studies are needed to optimize existing recommendations.

Validation of multiparametric approaches for the prediction of sudden cardiac death in patients with Brugada syndrome and electrophysiological study

INTRODUCTION AND OBJECTIVES

Multiparametric scores have been designed for better risk stratification in Brugada syndrome (BrS). We aimed to validate 3 multiparametric approaches (the Delise score, Sieira score and the Shanghai BrS Score) in a cohort with Brugada syndrome and electrophysiological study (EPS).

METHODS

We included patients diagnosed with BrS and previous EPS between 1998 and 2019 in 23 hospitals. C-statistic analysis and Cox proportional hazard regression models were used.

RESULTS

A total of 831 patients were included (mean age, 42.8±13.1; 623 [75%] men; 386 [46.5%] had a type 1 electrocardiogram (ECG) pattern, 677 [81.5%] were asymptomatic, and 319 [38.4%] had an implantable cardioverter-defibrillator). During a follow-up of 10.2±4.7 years, 47 (5.7%) experienced a cardiovascular event. In the global cohort, a type 1 ECG and syncope were predictive of arrhythmic events. All risk scores were significantly associated with events. The discriminatory abilities of the 3 scores were modest (particularly when these scores were evaluated in asymptomatic patients). Evaluation of the Delise and Sieira scores with different numbers of extra stimuli (1 or 2 vs 3) did not substantially improve the event prediction c-index.

CONCLUSIONS

In BrS, classic risk factors such as ECG pattern and previous syncope predict arrhythmic events. The predictive capabilities of the EPS are affected by the number of extra stimuli required to induce ventricular arrhythmias. Scores combining clinical risk factors with EPS help to identify the populations at highest risk, although their predictive abilities remain modest in the general BrS population and in asymptomatic patients.

Long-term prognosis of women with Brugada syndrome and electrophysiological study

BACKGROUND

A male predominance in Brugada syndrome (BrS) has been widely reported, but scarce information on female patients with BrS is available.

OBJECTIVE

The purpose of this study was to investigate the clinical characteristics and long-term prognosis of women with BrS.

METHODS

A multicenter retrospective study of patients diagnosed with BrS and previous electrophysiological study (EPS) was performed.

RESULTS

Among 770 patients, 177 (23%) were female. At presentation, 150 (84.7%) were asymptomatic. Females presented less frequently with a type 1 electrocardiographic pattern (30.5% vs 55.0%; P <.001), had a higher rate of family history of sudden cardiac death (49.7% vs 29.8%; P <.001), and had less sustained ventricular arrhythmias (VAs) on EPS (8.5% vs 15.1%; P = .009). Genetic testing was performed in 79 females (45% of the sample) and was positive in 34 (19%). An implantable cardioverter-defibrillator was inserted in 48 females (27.1%). During mean (± SD) follow-up of 122.17 ± 57.28 months, 5 females (2.8%) experienced a cardiovascular event compared to 42 males (7.1%; P = .04). On multivariable analysis, a positive genetic test (18.71; 95% confidence interval [CI] 1.82-192.53; P = .01) and atrial fibrillation (odds ratio 21.12; 95% CI 1.27-350.85; P = .03) were predictive of arrhythmic events, whereas VAs on EPS (neither with 1 or 2 extrastimuli nor 3 extrastimuli) were not.

CONCLUSION

Women with BrS represent a minor fraction among patients with BrS, and although their rate of events is low, they do not constitute a risk-free group. Neither clinical risk factors nor EPS predicts future arrhythmic events. Only atrial fibrillation and positive genetic test were identified as risk factors for future arrhythmic events.

Antitachycardia pacing for shock prevention in patients with hypertrophic cardiomyopathy and ventricular tachycardia

BACKGROUND

Hypertrophic cardiomyopathy (HCM) carries an increased risk of sudden death due to ventricular arrhythmias (VAs). The implantable cardioverter-defibrillator (ICD) is a well-established therapy for treatment of VA. Monomorphic ventricular tachycardias (MVTs) are frequent in HCM patients and suitable for antitachycardia pacing (ATP) termination.

OBJECTIVE

The purpose of this study was to describe ventricular tachycardia (VT) characteristics in a population of HCM patients with ICD and to study the effectiveness and safety of ATP for MVT.

METHODS

Data were obtained from the multicenter prospective observational UMBRELLA trial, which included all patients with HCM and ICD followed by the CareLink Monitoring System. All episodes of VA were collected and analyzed. ATP effectiveness and safety were described, and factors related to ATP effectiveness were studied with generalized estimating equation (GEE) models.

RESULTS

Among 251 patients followed for 47 months, 67 (26.7%) were implanted as secondary prevention. Fifty-six patients presented 326 episodes of VA (286 [87%] MVT). Mean cycle length was 312 ± 64 ms. Among 264 MVTs that received ICD therapy, 202 (76.5%) were ATP terminated. The first ATP burst was effective in 169 episodes (68.4%), and overall effectiveness of the first or second ATP burst was 73.8%. Multivariate GEE-adjusted analysis showed 2 variables related to ATP effectiveness: programming fast VT zone On vs Off (odds ratio [OR] 2.4; 95% confidence interval [CI] 1.5-5.2; P = .03) and programming ≥2 ATP bursts vs 1 burst only (OR 1.6; 95% CI 1.2-3.4; P = .04; and OR 2.9; 95% CI 1.8-6.3; P = .02; respectively).

CONCLUSION

MVT is the predominant VA in HCM patients with ICD. ATP is highly effective in terminating the majority of MVTs, and its proved effectiveness should guide device selection and programming in order to avoid unnecessary high-energy shocks.

Long-term prognosis of patients with life-threatening ventricular arrhythmias induced by coronary artery spasm

Aims

Coronary artery spasm (CAS) is associated with ventricular arrhythmias (VA). Much controversy remains regarding the best therapeutic interventions for this specific patient subset. We aimed to evaluate the clinical outcomes of patients with a history of life-threatening VA due to CAS with various medical interventions, as well as the need for ICD placement in the setting of optimal medical therapy.

Methods and results

A multicentre European retrospective survey of patients with VA in the setting of CAS was aggregated and relevant clinical and demographic data was analysed. Forty-nine appropriate patients were identified: 43 (87.8%) presented with VF and 6 (12.2%) with rapid VT. ICD implantation was performed in 44 (89.8%). During follow-up [59 (17-117) months], appropriate ICD shocks were documented in 12. In 8/12 (66.6%) no more ICD therapies were recorded after optimizing calcium channel blocker (CCB) therapy. SCD occurred in one patient without ICD. Treatment with beta-blockers was predictive of appropriate device discharge. Conversely, non-dihydropyridine CCB therapy was significantly protective against VAs.

Conclusion

Patients with life-threatening VAs secondary to CAS are at particularly high-risk for recurrence, especially when insufficient medical therapy is administered. Non-dihydropyridine CCBs are capable of suppressing episodes, whereas beta-blocker treatment is predictive of VAs. Ultimately, in spite of medical intervention, some patients exhibited arrhythmogenic events in the long-term, suggesting that ICD implantation may still be indicated for all.

Comparative Evaluation of Four Risk Scores for Predicting Mortality in Patients With Implantable Cardioverter-defibrillator for Primary Prevention

INTRODUCTION AND OBJECTIVES

Several clinical risk scores have been developed to identify patients at high risk of all-cause mortality despite implantation of an implantable cardioverter-defibrillator. We aimed to examine and compare the predictive capacity of 4 simple scoring systems (MADIT-II, FADES, PACE and SHOCKED) for predicting mortality after defibrillator implantation for primary prevention of sudden cardiac death in a Mediterranean country.

METHODS

A multicenter retrospective study was performed in 15 Spanish hospitals. Consecutive patients referred for defibrillator implantation between January 2010 and December 2011 were included.

RESULTS

A total of 916 patients with ischemic and nonischemic heart disease were included (mean age, 62 ± 11 years, 81.4% male). Over 33.4 ± 12.9 months, 113 (12.3%) patients died (cardiovascular origin in 86 [9.4%] patients). At 12, 24, 36, and 48 months, mortality rates were 4.5%, 7.6%, 10.8%, and 12.3% respectively. All the risk scores showed a stepwise increase in the risk of death throughout the scoring system of each of the scores and all 4 scores identified patients at greater risk of mortality. The scores were significantly associated with all-cause mortality throughout the follow-up period. PACE displayed the lowest c-index value regardless of whether the population had heart disease of ischemic (c-statistic = 0.61) or nonischemic origin (c-statistic = 0.61), whereas MADIT-II (c-statistic = 0.67 and 0.65 in ischemic and nonischemic cardiomyopathy, respectively), SHOCKED (c-statistic = 0.68 and 0.66, respectively), and FADES (c-statistic = 0.66 and 0.60) provided similar c-statistic values (P ≥ .09).

CONCLUSIONS

In this nontrial-based cohort of Mediterranean patients, the 4 evaluated risk scores showed a significant stepwise increase in the risk of death. Among the currently available risk scores, MADIT-II, FADES, and SHOCKED provide slightly better performance than PACE.

Etiology and Programming Effects on Shock Efficacy in ICD Recipients

BACKGROUND

We sought to assess the efficacy of high-energy shocks to restore rhythm and predictors of success in patients with sustained ventricular arrhythmias and implantable cardioverter defibrillator (ICD).

METHODS AND RESULTS

Data from 162 patients included in the UMBRELLA study that experienced one or more episodes of ventricular tachycardia (VT) for which ICD shocks of at least 30 Joules were delivered (appropriate high-energy shocks) were analyzed. In total, 456 ventricular arrhythmia episodes were registered. Forty four episodes (9.6%) from 39 patients (24%) had at least one ineffective high-energy shock delivered. Hypertrophic cardiomyopathy was more frequent among patients with unsuccessful shocks (10.3% vs 2.4%). Patients with ineffective shocks had higher proportion of sustained monomorphic ventricular arrhythmias (86.4%; the other 13.6% were sustained polymorphic and ventricular fibrillation [VF]) compared with patients with all their shocks effective (62.9%, P = 0.02). No statistical differences were found between groups in time from detection to the high-energy shock delivery, in tachycardia cycle length, or in antitachycardia pacing, but patients with ineffective high-energy shocks had higher proportion of previously ineffective low-energy shock (9.1% vs 0.5%, P = 0.01).

CONCLUSION

We found a substantial rate of ineffective high-energy shocks for the treatment of VT or VF in patients with ICD. High-energy shock efficacy seems to be reduced by hypertrophic cardiomyopathy and by the administration of previous low-energy shocks.

Spanish Catheter Ablation Registry. 12th Official Report of the Spanish Society of Cardiology Working Group on Electrophysiology and Arrhythmias (2012)

INTRODUCTION AND OBJECTIVES

This article presents the findings of the 2012 Spanish Catheter Ablation Registry.

METHODS

Data were collected in 2 ways: retrospectively using a standardized questionnaire, and prospectively using a central database. Each participating center selected its own preferred method of data collection.

RESULTS

Seventy-four Spanish centers voluntarily contributed data to the survey. A total of 11 042 ablation procedures were analyzed, averaging 149 (103) per center. The 3 main conditions treated were atrioventricular nodal reentrant tachycardia (n=2842; 25.7%), cavotricuspid isthmus (n=2485; 23%), and accessory pathways (n=1999; 18%). Atrial fibrillation was the fourth most common substrate treated (n=1852; 17%), representing a slight increase. The number of ventricular arrhythmia ablation procedures was similar to that of 2011, but there was a decrease in procedures for ventricular tachycardia associated with postinfarction scarring. The overall success rate was 94.9%, major complications occurred in 1.9%, and the overall mortality rate was 0.04%.

CONCLUSIONS

Data from the 2012 registry show that the number of ablations performed continued to increase. Overall, they also show a high success rate and a low number of complications. Ablation of complex substrates continued to increase, particularly in the case of atrial fibrillation.

Spanish Catheter Ablation Registry. 9th Report of the Spanish Society Of Cardiology Working Group on Electrophysiology and Arrhythmias (2009)

INTRODUCTION AND OBJECTIVES

This article reports the findings of the 2009 Spanish national Catheter Ablation Registry.

METHODS

Data were collected in two ways: retrospectively using a standard questionnaire and prospectively from a central database. Each center chose its own preferred method of data collection.

RESULTS

Data were collected from 59 centers. The total number of ablation procedures carried out was 8546, giving a mean of 145 ± 101 procedures per center. The three most frequently treated conditions were atrioventricular nodal reentrant tachycardia (n = 2341; 27%), typical atrial flutter (n = 1859; 21.7%) and accessory pathways (n = 1758; 20.5%). The fourth most common condition was atrial fibrillation (n = 1188; 14%), the number of which has grown by 44% since the 2008 registry. The overall success rate was 93%, major complications occurred in 1.9%, and the mortality rate was 0.046%.

CONCLUSIONS

Data from the 2009 registry show that the number of ablations carried out continued to increase and exceeded 8000 for the first time. In addition, they show, in general, a higher success rate and a lower number of complications. Cavotricuspid isthmus ablation, as treatment for typical atrial flutter, continued to be the second most common procedure. There was a substantial increase in the number of catheter ablations performed for atrial fibrillation compared with previous years.

Spanish Catheter Ablation Registry. 8th official report of the Spanish Society of Cardiology Working Group on Electrophysiology and Arrhythmias (2008)

INTRODUCTION AND OBJECTIVES

This article reports the findings of the 2008 Spanish Catheter Ablation Registry, as compiled by the Spanish Society of Cardiology Working Group on Electrophysiology and Arrhythmias.

METHODS

As in previous years, data were collected in two ways: retrospectively using a standard questionnaire sent to electrophysiology laboratories by the Working Group on Electrophysiology and Arrhythmias, and prospectively from a central database. Each participating center selected its own preferred method of data collection.

RESULTS

Fifty five Spanish centers contributed data voluntarily. In total, 7741 ablations were analyzed, averaging 141+/-97 per center. The three most frequently treated conditions were atrioventricular nodal reentrant tachycardia (n=2302; 31%), typical atrial flutter (n=1720; 22%) and accessory pathways (n=1658; 21%). The fourth most common condition was atrial fibrillation (n=829; 11%), which accounted for 18% more procedures than in 2007. Overall, the success rate was 93%, major complications occurred in 1.7%, and the mortality rate was 0.03%.

CONCLUSIONS

Registry data for 2008 show that the number of ablations carried out continues to increase, and has exceeded 7000 for the second time. In general, the success rate was high and there were few complications. Typical atrial flutter, requiring cavotricuspid isthmus ablation, has become the second most frequently treated condition. A moderate steady increase in the number of ablations for atrial fibrillation was also observed.

[Influence of cardiopathy etiology on responses to cardiac resynchronization therapy]

INTRODUCTION AND OBJECTIVES

Little is known about how responses to cardiac resynchronization therapy (CRT) are affected by the nature of the underlying cardiopathy. The aim of this study was to investigate how cardiopathy etiology influences the effect of CRT on reverse left ventricular remodeling.

METHODS

The study included 106 patients with left ventricular systolic dysfunction and left bundle branch block (LBBB) who were receiving CRT. Clinical and echocardiographic investigations were performed at baseline before implantation and at 6 and 12 month follow-up to determine left ventricular diameter, volume and systolic function, and to quantify mitral regurgitation.

RESULTS

During follow-up, it was observed that CRT reduced left ventricular volume and diameter, increased left ventricular ejection fraction (LVEF), and reduced mitral regurgitation severity irrespective of the etiology of the cardiopathy. In patients with ischemic dilated cardiomyopathy, LVEF increased by 34% and end-diastolic and end-systolic volumes decreased by 4% and 12%, respectively; in those with idiopathic dilated cardiomyopathy, LVEF increased by 38% and end-diastolic and end-systolic volumes decreased by 13% and 19%, respectively (P=NS for ischemic vs. non-ischemic disease). Nor were differences observed between the groups in clinical outcome: 74% of the ischemic group responded compared with 62% of the non-ischemic group (P=NS).

CONCLUSIONS

At 12-month follow-up, patients with left ventricular systolic dysfunction and LBBB treated by CRT showed clinical improvements and demonstrated reverse ventricular remodeling, irrespective of the etiology of their cardiopathy.

[Spanish catheter ablation registry. Sixth official report of the Spanish Society of Cardiology Working group on Electrophysiology and Arrhythmias (2006)]

INTRODUCTION AND OBJECTIVES

The findings of the 2006 Spanish Catheter Ablation Registry compiled by the Spanish Society of Cardiology Working Group on Electrophysiology and Arrhythmias are presented.

METHODS

As in previous years, data were collected in two ways: retrospectively using a standardized questionnaire sent to electrophysiology laboratories by the Working Group on Electrophysiology and Arrhythmias, and prospectively from a central database. Each participating center selected its own preferred method of data collection.

RESULTS

Forty-eight Spanish centers contributed data voluntarily. A total of 6568 ablation procedures were recorded, averaging 139+/-75 per center. As in previous reports, the three most frequently treated conditions were atrioventricular nodal reentrant tachycardia (n=1881, 28%), accessory pathways (n=1628, 25%), and typical atrial flutter (n=1507, 23%). Atrial fibrillation was the fourth most common condition treated (n=540, 8%). The overall success rate was 92.2%, major complications occurred in 1.4%, and the mortality rate was 0.015%.

CONCLUSIONS

In 2006, the number of ablation procedures recorded in the Spanish Catheter Ablation Registry continued to grow, with more than 6500 procedures now being registered. The success rate increased and there were fewer complications. Atrial fibrillation remains the fourth most common condition treated by catheter ablation at Spanish arrhythmia units.

Optimizing the programation of cardiac resynchronization therapy devices in patients with heart failure and left bundle branch block

This study was conducted to investigate the clinical impact of cardiac resynchronization device optimization. A series of 100 consecutive patients received cardiac resynchronization therapy. In the first 49 patients, an empirical atrioventricular delay of 120 ms was set, with simultaneous biventricular stimulation (interventricular [VV] interval=0 ms). In the next 51 patients, systematic atrioventricular optimization was performed. VV optimization was also performed, selecting 1 VV delay: right or left ventricular preactivation (+30 or -30 ms) or simultaneous (VV interval=0 ms), according to the best synchrony obtained by tissue Doppler-derived wall displacement. At follow-up, patients who were alive without cardiac transplantation and showed improvement of >or=10% in the distance walked in the 6-minute walking test were considered responders. There were no differences between the 2 groups at baseline. Left ventricular ejection fraction improved in the 2 groups, but left ventricular cardiac output improved only in the optimized group. At 6 months, patients with optimized devices walked slightly further in the 6-minute walking test (497+/-167 vs 393+/-123 m, p<0.01), with no differences in New York Heart Association functional class or quality of life compared with nonoptimized patients. Overall, the number of nonresponders were similar in the 2 groups (27% vs 23%, p=NS). In conclusion, the echocardiographic optimization of cardiac resynchronization devices provided a slight incremental clinical benefit at midterm follow-up. Simple and rapid methods to routinely optimize the devices are warranted.

Usefulness of ventricular dyssynchrony measured using M-mode echocardiography to predict response to resynchronization therapy

There are discordant data about the utility of septal-to-posterior wall motion delay (SPWMD) assessed using M-mode echocardiography to predict an improvement with cardiac resynchronization therapy (CRT). Baseline SPWMD was measured using M-mode in a parasternal short-axis view in a series of 67 patients undergoing CRT and followed up after 6 months. Heart failure was caused by coronary artery disease in 27 patients. Clinical responders were patients who were alive, had not undergone heart transplantation, and also increased the distance walked in 6 minutes by >10%. Baseline SPWMDs were mean 155 +/- 113 ms and median 135. Thirty-four patients (51%) had an SPWMD >130 ms. At 6-month follow-up, there were 17 nonresponders. At baseline, there were no significant differences between patients with SPWMD >130 or <130 ms in age, drug therapy, permanent atrial fibrillation, New York Heart Association functional class, underlying cause of cardiomyopathy, QRS duration, left ventricular (LV) ejection fraction, LV dimensions, or neurohormonal activation (norepinephrine and atrial and brain natriuretic peptide). At 6-month follow-up, baseline SPWMD was not associated with clinical response, New York Heart Association functional class, distance walked in 6 minutes, LV reverse remodeling, or neurohormonal activation. SPWMD >130 ms was also not a predictor. In conclusion, SPWMD is not a good predictor of response to CRT.

Cardiac resynchronization therapy: predictive factors of unsuccessful left ventricular lead implant

AIMS

Cardiac resynchronization therapy is an established therapy for advanced heart failure. However, coronary sinus access and pacing is not achieved in about 5-10% of patients. The aim of this study was to identify predictive factors for failure of left ventricular (LV) lead transvenous implant.

METHODS AND RESULTS

We evaluated 212 consecutive patients who received a cardiac resynchronization system. In 26 patients (12.3%), the attempt to pace the LV was unsuccessful. At univariate analysis, in patients with an unsuccessful implant a higher proportion of permanent atrial fibrillation (AF), valvular heart disease, and previous heart surgery were observed. Anteroposterior, longitudinal, and transversal left atrium diameters (LAD) were also larger among patients with an unsuccessful implant. The anteroposterior LAD (APLAD) with an optimal value to predict implant failure was 48.5 mm. At logistic regression analysis, the presence of permanent AF and APLAD were independent predictors of failed implant (OR 7.7, 95% CI 2.5-23.9, P=0.002 and OR 11.7, 95% CI 3.1-37.6, P<0.001, respectively).

CONCLUSION

The presence of permanent AF and APLAD are factors that predict unsuccessful pacing from the LV.

Relation of response to cardiac resynchronization therapy to left ventricular reverse remodeling

Cardiac resynchronization therapy (CRT) reverses left ventricular (LV) remodeling in patients with congestive heart failure. However, the mechanisms leading to the clinical response to CRT remain unclear. The aim of this study was to analyze whether patients who improve clinically have greater LV reverse remodeling than nonresponders after a 12-month follow-up period. The sample comprised 64 consecutive patients with heart failure, complete left bundle branch block, and LV ejection fractions (EFs) < or =35% who were treated with CRT. Doppler echocardiographic scans were taken just before and immediately after the implantation of the pacemakers and at 6- and 12-month follow-up examinations. LV diameters, volumes, and EFs were compared. Responders were defined as those patients who were alive without cardiac transplantation and with > or =10% improvement in the 6-minute walking test after 1 year of follow-up. There were no clinical differences at baseline between responders and nonresponders. At 6- and 12-month follow-up, LV dimensions decreased significantly in responders but did not change in nonresponders. Furthermore, LVEFs improved only in responders. In conclusion, patients who clinically respond to CRT have greater LV reverse remodeling than nonresponders after 6 and 12 months of follow-up. The effect of CRT on LV remodeling may explain, at least in part, the clinical benefit of this therapy.

Diphenhydramine overdose and Brugada sign

We report a case of electrocardiographic signature of the Brugada syndrome in a 39-year-old patient with an overdose of diphenhydramine. He was found unconscious and hypotensive. His serum potassium concentration was 8.3 mEq/L and the ECG revealed a coved-type ST-segment elevation in leads V2-V3. These repolarization abnormalities neither normalize with the correction of the hyperkalemia nor with an intravenous infusion of isoproterenol. When he regained consciousness, he was admitted the toxic ingestion of diphenhydramine and progressively the ECG normalized. A negative flecainide test confirmed that the transient ECG abnormalities were the consequence of the drug overdose and ruled out the Brugada syndrome.

Predictors of lack of response to resynchronization therapy

About 30% of patients treated with cardiac resynchronization therapy (CRT) do not respond to treatment. The aim of this study was to identify clinical predictors of lack of improvement in patients receiving CRT. From 197 consecutive patients scheduled to receive CRT, 143 fulfilled the inclusion criteria. Mean age was 68 +/- 7 years and 79% were men. Heart failure was due to ischemic heart disease in 49 patients (34%). Mean QRS duration was 165 +/- 26 ms, and left ventricular ejection fraction was 27 +/- 7%. Nonresponder patients were defined as those who died of heart failure, underwent heart transplantation, or did not increase the distance walked in 6 minutes >10%. At 6-month follow-up, there were 28 nonresponders (20%). Among nonresponders, 2 patients received a heart transplantation and 9 patients died of heart failure. In logistic regression analysis, independent predictors of lack of response to CRT were ischemic heart disease (odds ratio [OR] 2.9, 95% confidence interval [CI] 1.2 to 7; p = 0.023), severe mitral regurgitation (OR 3.5, 95% CI 1.3 to 9; p = 0.014), and left ventricular end-diastolic diameter > or =75 mm (OR 3.1, 95% CI 1.1 to 8; p = 0.026). Patients with these 3 predictors had a probability response of 27%.

[Predictors of lack of clinical improvement at mid-term follow-up with cardiac resynchronization therapy]

INTRODUCTION

About 30% of all patients do not respond to cardiac resynchronization therapy for heart failure. The objective of the study was to analyze the variables that may predict the lack of response.

PATIENTS AND METHOD

We analyzed the results in a series of 63 patients who received cardiac resynchronization with a biventricular device. Clinical and left ventricular function parameters were evaluated at the beginning of the study and at 6 months. Responders were defined as those who were alive, had not received a heart transplant, and who achieved more than a 10% increase in distance in the 6-minute walking test.

RESULTS

Mean age was 68.3 (8) years, 51 patients (81%) were men, and NYHA functional class was III-IV in 79.4%. Mean left ventricular ejection fraction was 22.4% (6)%, QRS width was 177 (25) ms, and 77.8% were in sinus rhythm. Almost half (46%, n=29) had ischemic heart disease. At 6-month follow-up, 69.8% of the patients were responders. Ischemic heart disease, sustained monomorphic ventricular tachycardia and a degree of mitral regurgitation >II/IV before implantation were associated with lack of response. No association was found for any of the other baseline variables. Logistic regression analysis identified all three of the aforementioned variables as independent predictors of lack of response: ischemic heart disease OR=4.8, 95% CI, 1.2-18.3, P=.023; ventricular tachycardia OR=8.7, 95% CI, 1.8-41.3, P=.007; and mitral regurgitation OR=8.03, 95% CI, 1.7-37.1, P=.008.

CONCLUSION

The likelihood of responding to resynchronization therapy is lower in patients with ischemic heart disease, significant mitral regurgitation, or sustained monomorphic ventricular tachycardia.