Role of arrhythmic phenotype in prognostic stratification and management of dilated cardiomyopathy

AIMS

Dilated cardiomyopathy (DCM) with arrhythmic phenotype combines phenotypical aspects of DCM and predisposition to ventricular arrhythmias, typical of arrhythmogenic cardiomyopathy. The definition of DCM with arrhythmic phenotype is not universally accepted, leading to uncertainty in the identification of high-risk patients. This study aimed to assess the prognostic impact of arrhythmic phenotype in risk stratification and the correlation of arrhythmic markers with high-risk arrhythmogenic gene variants in DCM patients.

METHODS AND RESULTS

In this multicentre study, DCM patients with available genetic testing were analysed. The following arrhythmic markers, present at baseline or within 1 year of enrolment, were tested: unexplained syncope, rapid non-sustained ventricular tachycardia (NSVT), ≥1000 premature ventricular contractions/24 h or ≥50 ventricular couplets/24 h. LMNA, FLNC, RBM20, and desmosomal pathogenic or likely pathogenic gene variants were considered high-risk arrhythmogenic genes. The study endpoint was a composite of sudden cardiac death and major ventricular arrhythmias (SCD/MVA). We studied 742 DCM patients (45 ± 14 years, 34% female, 410 [55%] with left ventricular ejection fraction [LVEF] <35%). During a median follow-up of 6 years (interquartile range 1.6-12.1), unexplained syncope and NSVT were the only arrhythmic markers associated with SCD/MVA, and the combination of the two markers carried a significant additive risk of SCD/MVA, incremental to LVEF and New York Heart Association class. The probability of identifying an arrhythmogenic genotype rose from 8% to 30% if both early syncope and NSVT were present.

CONCLUSION

In DCM patients, the combination of early detected NSVT and unexplained syncope increases the risk of life-threatening arrhythmic outcomes and can aid the identification of carriers of malignant arrhythmogenic genotypes.

Long-term clinical outcomes of patients with drug-induced type 1 Brugada electrocardiographic pattern: A nationwide cohort registry study

BACKGROUND

There are limited real-world data on the extended prognosis of patients with drug-induced type 1 Brugada electrocardiogram (ECG).

OBJECTIVE

We assessed the clinical outcomes and predictors of life-threatening arrhythmias in patients with drug-induced type 1 Brugada ECG.

METHODS

This multicenter retrospective study, conducted at 21 Italian and Swiss hospitals from July 1997 to May 2021, included consecutive patients with drug-induced type 1 ECG. The primary outcome, a composite of appropriate ICD therapies and sudden cardiac death, was assessed along with the clinical predictors of these events.

RESULTS

A total of 606 patients (mean age 49.7 ± 14.7 years; 423 [69.8%] men) were followed for a median of 60.3 months (interquartile range 23.0-122.4 months). Nineteen patients (3.1%) experienced life-threatening arrhythmias, with a median annual event rate of 0.5% over 5 years and 0.25% over 10 years. The SCN5A mutation was the only predictor of the primary outcome (hazard ratio 4.54; P = .002), whereas a trend was observed for unexplained syncope (hazard ratio 3.85; P = .05). In patients who were asymptomatic at presentation, the median annual rate of life-threatening arrhythmias is 0.24% over 5 years and increases to 1.2% if they have inducible ventricular fibrillation during programmed ventricular stimulation.

CONCLUSION

In patients with drug-induced type 1 Brugada ECG, the annual risk of life-threatening arrhythmias is low, with the SCN5A mutation as the only independent predictor. Unexplained syncope correlated with worse clinical outcomes. Ventricular fibrillation inducibility at programmed ventricular stimulation significantly increases the median annual rate of life-threatening arrhythmias from 0.24% to 1.2% over 5 years.

The association between patent foramen ovale and unexplained syncope in pediatric patients

BACKGROUND

Patent foramen ovale (PFO) is associated with transient ischemia attack (TIA) or stroke, paradoxical embolism, and migraines. PFO closure decreases the recurrent incidence of cerebral ischemic events and reduces the incidence of syncope in adults. However, whether PFO is associated with syncope in pediatric patients has not been investigated.

METHODS

1001 pediatric patients (aged 4 to 17 years, mean age 10.31 ± 2.61 years, 519 males) who complained of unexplained syncope, palpitation, headache, dizziness and chest pain and were hospitalized in the Syncope Ward, The Second Xiangya Hospital, Central South University between January 2013 and April 2022 were recruited. Children with definite etiology of syncope, neurological, cardiogenic, psychological and other system diseases were excluded. PFO was measured by transthoracic echocardiography and right-heart contrast echocardiography was performed to identify the presence of right-to-left shunting. The demographic data and medical records were retrospectively reviewed and analyzed.

RESULTS

276 cases were included in the simple syncope group, 379 cases in the headache/dizziness group, 265 cases in the chest pain group, and 81 cases in the palpitation group. The incidence of PFO between the four groups was insignificant (4.71%, 4.74%, 4.15%, 6.17%, respectively, P = 0.903). Multivariate Logistic regression demonstrated that PFO is not associated with the increased risk of syncope (P = 0.081).

CONCLUSION

PFO may not increase the risk of syncope in pediatric patients. Further study may include a large and multicenter sample to investigate the association between PFO and unexplained syncope.

Twenty-five years of research on syncope

Over the last 25 years, the Europace journal has greatly contributed to dissemination of research and knowledge in the field of syncope. More than 400 manuscripts have been published in the journal. They undoubtedly improved our understanding of syncope. This symptom is now clearly differentiated from other forms of transient loss of consciousness. The critical role of vasodepression and/or cardioinhibition as final mechanisms of reflex syncope is emphasized. Current diagnostic approach sharply separates between cardiac and autonomic pathways. Physiologic insights have been translated, through rigorously designed clinical trials, into non-pharmacological or pharmacological interventions and interventional therapies. The following manuscript is intended to give the reader the current state of the art of knowledge of syncope by highlighting landmark contributions of the Europace journal.

Definitive aetiology of unexplained syncope after cardiovascular autonomic tests in a tertiary syncope unit

AIMS

Syncope is a common condition with many possible causes, ranging from benign to life-threatening aetiologies. Establishing a diagnosis can be difficult, and specialized syncope units, using cardiovascular autonomic tests (CATs), including a head-up tilt test, can increase the diagnostic yield. However, up to one-fifth of examined patients have inconclusive CAT results. The aim of the present study was to investigate the predictive value of history, and clinical findings for unexplained syncope after CAT and characterize the group with negative results.

METHODS AND RESULTS

Consecutive syncope patients [n = 2663, 61% women, median age 52 (32-69) years] were evaluated and CAT explained aetiology of syncope in 79% of cases, whereas 21% remained unexplained. Predictors of negative CAT were older age at first syncope (+8% higher odds per 10-year increment, P = 0.042), higher supine heart rate (HR; +12% per 10 b.p.m.; P = 0.003), absence of prodromes (+48%; P < 0.001), hypertension (+45%; P = 0.003), diabetes (+82%; P < 0.001), heart failure (+98%; P = 0.014), and coronary artery disease (+51%; P = 0.027). Compared with vasovagal syncope, patients with negative CAT were older, reported more often the absence of prodromes, and had a higher burden of cardiovascular comorbidities.

CONCLUSION

A cardiovascular autonomic test established the cause of syncope in 79% of patients evaluated in a syncope unit. Syncope without prodromes and cardiovascular comorbidities were significant predictors of failure to reveal an aetiology from assessment by CAT. These are known risk factors for cardiac syncope and patients with inconclusive CAT warrant further investigation.

The clinical presentation of syncope influences the head-up tilt test responses

INTRODUCTION

Little is still known about the positivity rate of nitroglycerin (NTG) potentiated head-up tilt test (HUTT) according to the history-based clinical features of syncope. The study aimed to compare the HUTT positivity rate and type of responses in patients with classical and non-classical vasovagal syncope (VVS).

MATERIALS AND METHODS

We retrospectively evaluated all consecutive patients who underwent NTG-potentiated HUTT for VVS. The study population was dichotomized into classical and non-classical VVS.

RESULTS

A total of 1285 VVS patients (45± 19.1 years; 49.6% male) were enrolled: 627 (48.8%) had a history of classical VVS and 658 (51.2%) of non-classical VVS. HUTT was positive in 866 (67.4%) patients. The positivity rate was significantly higher in patients with classical compared to those with non-classical VVS (81.5% vs 54%; P< 0.0001). Cardioinhibitory response showed similar total positivity rate (27.6% vs 31%; P= 0.17), but higher relative prevalence among positive tests (57.7% vs 33.9%, P< 0.0001) in patients with non-classical VVS. At multivariable analysis, classical reflex syncope, male sex, history of traumatic syncope and use of diuretics were independent predictors of HUTT positivity.

CONCLUSION

The clinical presentation of syncope influences the overall HUTT positivity rate and the type of responses. Cardioinhibitory response and traumatic syncope are more likely in patients with non-classical VVS.

Ventricular conduction delay as marker of risk in Brugada Syndrome. Results from the analysis of clinical and electrocardiographic features of a large cohort of patients

BACKGROUND

Brugada Syndrome is a genetic arrhythmogenic disease with a variable clinical spectrum. The role of clinical and ECG parameters in the risk stratification is still uncertain.

AIMS

In a large cohort of Brugada patients we analysed clinical and ECG features to determine the variables with prognostic value for the occurrence of a first documented arrhythmic event and for recurrences.

METHODS

We enrolled 614 patients, subdivided into 3 groups according to their clinical presentation: 531 (88%) asymptomatic, 69 (10%) with previous unexplained syncope and 14 (2%) with aborted sudden death. We also compared the ECG characteristics of patients with a single documented arrhythmic event (either at presentation or at follow-up, 17 patients), with those of patients with arrhythmic recurrences (13 patients).

RESULTS

The event rate was 1.3% in the asymptomatic patients and 15% among patients with unexplained syncope (median follow-up 6 years), p < 0.0001. In both groups a QRS duration ≥110 ms in lead II and/or V6 and/or S wave duration ≥40 ms in lead I and/or II were significant risk factors for the occurrence and timing of events at follow-up. The same ECG risk factors were also significantly associated with arrhythmic recurrences.

CONCLUSIONS

The arrhythmic risk of Brugada patients is related not only to the symptoms at presentation, but also to the presence of a ventricular conduction delay (QRS duration ≥ 110 ms and/or S wave duration ≥ 40 ms). The ECG conduction parameters also affect the timing of events and recurrences.

Different haemodynamic patterns in head-up tilt test on 400 paediatric cases with unexplained syncope

OBJECTIVE

To assess haemodynamic patterns in head-up tilt testing on 400 paediatric cases with unexplained syncope.

METHODS

Medical records of 520 children who underwent head-up tilt testing in the preceding year were retrospectively evaluated, and 400 children, 264 (66%) girls and 136 (34%) boys, aged 12.6±2.6 years (median 13; range 5-18), with unexplained syncope were enrolled in the study. Age, sex, baseline heart rate, baseline blood pressure, frequency of symptoms, and/or fainting attacks were recorded. The test protocol consisted of 25 minutes of supine resting followed by 20 minutes of 70° upright positioning. Subjects were divided into nine groups according to their differing haemodynamic patterns.

RESULTS

There were no statistically significant differences between the groups with regard to age, gender, baseline blood pressure, and frequency of syncope (p>0.05). The response was compatible with orthostatic intolerance in 28 cases (7.0%), postural orthostatic tachycardia syndrome in 24 cases (6.0%), asymptomatic postural orthostatic tachycardia syndrome in 26 cases (6.5%), orthostatic hypotension in seven cases (1.7%), vasovagal syncope in 38 cases (9.5%), and negative in 274 cases (69.2%). Vasovagal syncope response patterns were of type 3 in nine cases (2.2%), type 2A in 10 cases (2.5%), type 2B in two cases (0.5%), and type 1 (mixed) in 17 cases (4.25%).

CONCLUSIONS

In the 400 paediatric cases with unexplained syncope, nine different haemodynamic response patterns to head-up tilt testing were discerned. Children with orthostatic intolerance syndromes are increasingly referred to hospitals because of difficulty in daily activities. Therefore, there is need for further clinical trials in these patient groups.

Single center experience in Japanese patients with syncope

BACKGROUND AND PURPOSE

The present diagnostic method and features of syncope in Japan are unclear. Implantable loop recorder (ILR) and head-up tilt tests have recently become available for diagnosing syncope. The examination method and rates of diagnosing syncope may vary. This study aimed to clarify the present diagnostic method and features of syncope in a single Japanese medical center.

METHODS AND RESULTS

We retrospectively reviewed the medical records of consecutive patients who were seen at our hospital from January 1, 2009, to December 31, 2012. A total of 547 patients (328 men, 60.4±21.5 years) with syncope were seen at our hospital. Reflex syncope was diagnosed in 29.1% of the cases, orthostatic hypotension in 11.7%, cardiac syncope in 34.0%, and unexplained syncope in 23.9% by initial and early evaluations. The number of patients with situational syncope and orthostatic hypotension that could be diagnosed in the initial evaluation of the first examination was significantly greater than that in subsequent evaluations. Forty-three percent of the unexplained syncope patients received an ILR. The consent rate for ILR implantations in the unexplained syncope patients with a suspected arrhythmia nature was 53.1%. The cumulative ILR diagnostic rates were 47% and 65% at 1 and 2 years after the ILR implantation, respectively. The estimated ILR diagnostic rates were significantly greater than that for conventional test without using an ILR. When patients with unexplained syncope could be diagnosed, the recurrent symptoms were greatly reduced.

CONCLUSIONS

Syncope is induced by various causes in Japan. It is important that we understand the characteristics of each syncope cause. The consent rate for implanting an ILR in appropriate unexplained syncope patients is low. We need to educate these patients about the importance of making a diagnosis of syncope.

Randomized Prospective Comparison of Two Protocols for Head-up Tilt Testing in Patients with Normal Heart and Recurrent Unexplained Syncope

BACKGROUND

This randomized study was aimed to compare the diagnostic value of two head-up tilt testing protocols using sublingual nitroglycerin for provocation in patients with recurrent unexplained syncope and normal heart.

METHODS

The patients with normal findings in physical examination, electrocardiography and echocardiography were randomly submitted to one of upright tilt test protocols. The only difference between two protocols was that nitroglycerin was administered after a five minute resting phase in supine position during protocol B. We also considered eighty normal persons as the control group.

RESULTS

Out of 290 patients that underwent tilt testing, 132 patients were in group A versus 158 patients in group B. Both groups had an identical distribution of clinical characteristics. Tilt test was positive in 79 patients in group A (25 in passive phase, 54 in active phase) versus 96 patients in group B (43 in passive phase, 53 in active phase). There was no significant difference between results in two groups (P value= 0.127). Forty cases were tested with protocol A and forty underwent tilt testing with protocol B. Tilt test was positive in 4 cases with protocol A versus 3 cases in protocol B. The positive rates of tilt testing with protocol A was 60% while it was 61% in protocol B. The specificity of testing with protocol A was 90% and it was 92.5% in protocol B.

CONCLUSIONS

According to our data, adding a period of rest and returning to supine position before nitroglycerin administration had no additional diagnostic yield.

[Diagnostic and prognostic value of the head-up tilt test for patients with unexplained syncope: results of a French survey]

OBJECTIVE

Evaluate the diagnostic and prognostic input of head-up tilt test in the exploration of unexplained syncope.

METHOD

Between January 2009 and December 2012, all patients undergoing a head-up tilt test for recurrent syncope were studied. Follow-up data were obtained using telephone interviews and medical record reviews.

RESULTS

A head-up tilt test was realized in 77 patients (47.8±20years, 53% female) for an exploration of syncope. The tilt test elicited syncope or pre-syncope in 57 patients (74%). The positive response included vaso-vagal syncope in 53 patients and psychogenic syncope in 4 patients. After a mean follow-up of 32±11months (range 6-54months), 90% of patients had not a recurrence of syncope. Of note, the incidence of recurrence was the same regardless of whether the patients had a positive (n=5/48; 10%) or a negative head-up tilt test response (n=2/19; 10%).

CONCLUSION

The tilt test has a certain diagnostic value in the exploration of unexplained syncope. Recurrence rate of syncope after a tilt test is low. However, our study suggests no correlation between head-up tilt test results and the likelihood of recurring syncope.