Is there an isolated arrhythmogenic right atrial myocarditis?

Isolated Atrial Neutrophilic Myocarditis: A Rare Cause of Death and Potential "Blind Spot" for Postmortem Computed Tomography and Postmortem Examination

ABSTRACT

Myocarditis can focally or diffusely involve the myocardium and is associated with arrhythmia, cardiac failure, and sudden death. The majority of cases of myocarditis are lymphocytic in etiology, and neutrophilic myocarditis is relatively uncommon. Although reported in lymphocytic myocarditis, isolated/focal neutrophilic myocarditis of the atrium causing death is not reported in the postmortem literature, and its postmortem computed tomography correlation is not documented. We report a fatal case of isolated neutrophilic atrial myocarditis affecting only the left atrium in a 33-year-old woman presenting as a sudden unexpected death. Microscopy of the left atrium, a not commonly sampled area of the heart, showed florid neutrophilic myocarditis with the remaining right atrium, conduction system, and both ventricles uninvolved. Similar to previously reported fatal isolated atrial lymphocytic myocarditis, postmortem computed tomography was unable to detect any atrial abnormalities. This case highlights a potential "blind spot" for both routine postmortem imaging and examination.

Atrial myocarditis as a cause of sinus arrest in a dog

A 10-year-old male cairn terrier cross was presented with a history of myxomatous mitral valve disease diagnosed six months previously and with a four-week history of intermittent collapse. On 24 hour electrocardiograph (Holter) analysis, periods of no discernable electrical cardiac activity, which coincided with three collapsing episodes, were identified. Unfortunately, on re-presentation for removal of the Holter monitor, the dog collapsed and died. A post-mortem examination was conducted, and histology of the right and left atrium showed evidence of myocarditis. This is the first reported case, to our knowledge, of collapse because of electrical asystole in a dog with atrial myocarditis.

Upstream Therapy for Atrial Fibrillation

There are multiple factors for the etiology of atrial fibrillation (AF), including stretch, autonomic imbalance, hyperthyroidism, and inflammation. Of these factors for AF, stretch and inflammation increase the angiotensin II level, thereby inducing calcium over load, and inducing ectopic focal activities that initiate AF. Angiotensin II activates the Erk cascade through the AT(1)R and induces interstitial fibrosis of the atria, which compromises intra-atrial conduction. Short atrial refractoriness and slow conduction form multiple re-entry, before maintaining AF. Anti-arrhythmic drugs used for downstream therapy can suppress the focal activities and re-entry, but cannot prevent the development of a structural substrate. In contrast, angiotensin-converting enzyme, angiotensin II type 1 receptor blocker and statins might constitute upstream therapy through the prevention of structural remodeling that promotes AF.

Lipid-lowering therapy with statins, a new approach to antiarrhythmic therapy

Inhibitors of 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase (statins) are the most effective and best-tolerated drugs to treat elevated levels of low-density lipoprotein cholesterol (LDL-C). In addition, they exhibit other effects unrelated to their lipid lowering effects (pleiotropic actions). In recent years, experimental and clinical evidence demonstrates that statins exert antiarrhythmic properties, reducing the recurrences of supraventricular and life-threatening ventricular arrhythmias both in patients with and without coronary artery disease (CAD). Thus, statins may constitute a novel therapeutic approach to cardiac arrhythmias. This article reviews the antiarrhythmic properties of statins as well as the possible mechanisms involved, including the lowering of LDL-C levels, the improvement of endothelial dysfunction and autonomic function, the stabilization of the atherosclerotic plaques, the antioxidant, antiinflammatory, antithrombotic and cardioprotective properties and the modulation of transmembrane ion fluxes.

Statin Use before By-Pass Surgery Decreases the Incidence and Shortens the Duration of Postoperative Atrial Fibrillation

BACKGROUND

The aim of the present observational study is to search the incidence of postoperative atrial fibrillation (AF) in patients with or without preoperative statin treatment.

METHODS AND RESULTS

The population consisted of 362 consecutive patients (267 on and 95 not on statin). Diabetes mellitus was more frequent in statin group (p = 0.03). Other demographic and procedural variables were similar in the both groups (All p > 0.05). Postoperative AF was less frequent and its duration was shorter in statin group compared to non-statin group (p = 0.03 and 0.0001, respectively). The Kaplan-Meier analysis showed the protective effect of statins against the risk of developing AF (p = 0.01).

CONCLUSION

Statin treatment before the by-pass surgery decreases the incidence and shortens the duration of postoperative AF.

Electroanatomical Mapping (CARTO) of ectopic atrial tachycardia: impact of bipolar and unipolar local electrogram annotation for localization the focal origin

Electroanatomical Mapping (CARTO) allows a tridimensional localization of ectopic atrial tachycardia (EAT). No standardized recommendation exists for annotation the local activation time in EAT using this new technology. In the present study bipolar local electrogram were used for CARTO guided RF ablation of EAT. In comparison the same maps were retrospectively analyzed by annotation the unipolar local electrogram.

METHODS

In 15 consecutive patients (6m, 51+/-14 y) with EAT CARTO mapping was guided by annotation the earliest onset of the bipolar local electrogram. Following successful RF ablation the obtained EAT maps were subsequently evaluated by annotation of the earliest steepest negative intrinsic deflection of the unipolar local electrogram. Both CARTO maps were compared with regard to the region of focal EAT origin.

RESULTS

RF ablation of all 15 EAT foci guided by annotation the bipolar local electrogram with CARTO was successful with a median of 3 [1-18] pulses and a median fluoroscopy time of 10 min [4-25]. All but one focus was located in the right atrium: posterior to posteroinferior region of the terminal crest in 6, septal region in 5, anterior superior region in 3 cases. One left sided EAT was located at the septum. The bipolar CARTO map demonstrated a "small territory" location of earliest activation (extension of the focus < or =0.4 cm(2)) in 14 out of 15 patients. In a single patient the bipolar map showed several sites of earliest local activation (extension >0.4 cm(2)). On the other side the retrospectively achieved unipolar maps demonstrated an extended region of earliest local activation in 6 out of 15 patients (>0.4 cm(2)).

CONCLUSIONS

CARTO maps of EAT by annotation the earliest onset of the bipolar local electrogram provide an efficacious guide for location the focal origin. Extended regions of earliest local activation in EAT might be rather determined by annotation the unipolar in comparison to the bipolar local electrogram.

Ventricular preexcitation in children and young adults: atrial myocarditis as a possible trigger of sudden death

BACKGROUND

Sudden death (SD) in ventricular preexcitation (VP) syndrome is believed to be the result of atrial fibrillation with rapid ventricular response over the accessory pathway. Previous reports are anecdotal and often lack autopsy validation.

METHODS AND RESULTS

Prevalence and clinicopathological features of VP were investigated in a series of 273 SDs in children and young adults (aged <or=35 years). Site of accessory atrioventricular (AV) connection was predicted by 12-lead ECG. Right and left AV ring together with the sinoatrial and AV septal junction were studied in serial histological sections. Ten patients (3.6%; male, mean age 24+/-7 years) had VP: 8 had Wolff-Parkinson-White (WPW) and 2 had Lown-Ganong-Levine (LGL) syndrome. Six patients had previous symptoms, and SD occurred at rest in all but 1. Pathological substrates of LGL consisted of AV-node hypoplasia and right-sided atrio-Hisian tract, respectively. In the 8 WPW patients, 10 total accessory AV pathways consisting of ordinary myocardium were found (7 left lateral, 2 right posterolateral, and 1 septal). These pathways were close to the endocardium (mean distance, 750+/-530 microm) and 310+/-190 microm thick. In 4 WPW patients (50%), isolated acute atrial myocarditis was found, which was polymorphous in 1 and lymphocytic in 3.

CONCLUSIONS

VP accounted for 3.6% of SD in young people and was not preceded by warning symptoms in 40%. A left accessory pathway was the most frequent substrate, and its subendocardial location supports the feasibility of catheter ablation. Isolated atrial myocarditis may act as a trigger of paroxysmal atrial fibrillation that leads to SD.

Increased atrial vulnerability in arrhythmogenic right ventricular disease

Supraventricular tachyarrhythmias (SVTA) may occur in patients with the arrhythmogenic right ventricular dysplasia (ARVD). The purpose of the study was to evaluate the incidence of SVTA in 47 patients with ARVD proved by right ventricular angiography. Thirty-three men and 14 women, aged 21 to 72 years (mean 44 +/- 18) were admitted for nonsustained or sustained ventricular tachycardia. Eight patients had a history of spontaneous SVTA several years before ventricular tachycardia occurrence. Protocol of the study consisted of programmed atrial stimulation with one and two extrastimuli delivered during sinus rhythm and two driven rhythms (600 and 400 msec), programmed ventricular stimulation with up to three extrastimuli and was performed in the control state and after infusion of isoproterenol. The results of programmed atrial stimulation were compared with those obtained in 36 asymptomatic subjects without heart disease and with a mean age of 50 +/- 18 years (control group). Sustained SVTA (> 1 minute) was induced in seven of eight patients with spontaneous SVTA, in 27 (69%) of those with ARVD, who did not have spontaneous SVTA, and in two control subjects (5.5%) (p < 0.001). SVTA was inducible in the control state, but ventricular tachycardia induction required isoproterenol in 11 of 27 patients. Two patients without SVTA history but with inducible SVTA developed later spontaneous SVTA. ARVD was associated with a significantly higher incidence of inducible SVTA than in a control population. Supraventricular tachycardias may precede ventricular tachycardias. This association argues for a diffuse myocardial disorder in ARVD.

Histological substrate of atrial biopsies in patients with lone atrial fibrillation

BACKGROUND

Lone atrial fibrillation (LAF) is a common clinical syndrome, but its origin remains unknown.

METHODS AND RESULTS

We performed endomyocardial biopsies of the right atrial septum (2 to 3 per patient; mean, 2.8) and of the two ventricles (6 per patient) in 12 patients (10 men, 2 women; mean age, 32 years) with paroxysmal LAF refractory to conventional antiarrhythmic treatment. As controls, we used endomyocardial biopsies (3 to 5 per patient; mean, 4.4) from the right atrial septum of 11 patients with Wolff-Parkinson-White syndrome (WPW) undergoing resection of the abnormal AV pathway. The weight of the biopsies ranged from 2.8 to 4.5 mg. Biopsy samples were processed for histology and electron microscopy and were read by a pathologist blinded to clinical data. All patients underwent two-dimensional Doppler echocardiography; cardiac catheterization; coronary angiography; and hormonal, virologic, and electrophysiological studies. All tests and WPW biopsies were normal, but all LAF atrial biopsy specimens (average, 2.8 per patient) showed abnormalities (P<.0001). The type of abnormalities varied: Two patients had a severe hypertrophy with vacuolar degeneration of the atrial myocytes and ultrastructural evidence of fibrillolysis occupying >50% of the areas assessed morphometrically (P=.50), 8 had lymphomononuclear infiltrates with necrosis of the adjacent myocytes (5 with fibrosis and 3 without; P<.003), and 2 had only nonspecific patchy fibrosis (P=.50). Biventricular biopsies were abnormal in only 3 patients and showed inflammatory infiltrates similar to those found in atrial biopsies.

CONCLUSIONS

Abnormal atrial histology was uniformly found in multiple biopsy specimens in all patients with LAF. It was compatible with a diagnosis of myocarditis in 66% of patients (active in 25%) and of noninflammatory localized cardiomyopathy in 17% and was represented by patchy fibrosis in 17%. The cause of the pathological changes, which were found only in atrial septal biopsies but not in biventricular biopsies, in 75% of patients remains unknown.

Biopsy evidence of atrial myocarditis in an athlete developing transient sinoatrial disease

Atrial myocarditis causing transient sinoatrial disease (incessant atrial tachycardia alternating with sinoatrial pauses of up to 6 s in duration) in an athlete is reported. Diagnosis was undertaken by endomyocardial biopsy; biventricular and right atrial specimens were obtained. After a 6-month rest period, the atrial arrhythmias disappeared, and the athlete was able to resume his professional sporting activities.

Role of myocarditis in athletes with minor arrhythmias and/or echocardiographic abnormalities

We report the clinical and instrumental data, including the endomyocardial biopsy findings, of six young athletes presenting with minor arrhythmias and/or echocardiographic abnormalities. In one of them, a left ventricular dilation with moderate depression of the systolic function had been attributed to an athlete's heart. A diagnosis of arrhythmogenic right ventricular dysplasia had been made in three others, one with right ventricular dilation and apical hypokinesia, and two with ventricular arrhythmias with QRS morphology of left bundle branch block. A myocarditis could be unequivocally established in four athletes (two with and two without fibrosis). In the remaining two, with a clinical history strongly suggesting a previously acute myocarditis, the endomyocardial biopsy specimen revealed a nonspecific fibrosis compatible but not definitely pathognomonic of a healed myocarditis. Our report suggests that a myocarditis may be a cause of minor rhythm disturbances and/or echocardiographic abnormalities in athletes. A prevalent localization of the inflammatory process in the right ventricle with or without the occurrence of ventricular arrhythmias with left bundle branch block morphology can mimic an arrhythmogenic right ventricular dysplasia. An early diagnosis of myocarditis in athletes is useful to avoid the risk of fatal arrhythmias, also considering that rest still keeps on being one of the most effective strategies in myocarditis management.