Cardiac magnetic resonance imaging: diagnostic value and utility in the follow-up of patients with acute myocarditis mimicking myocardial infarction.

PURPOSE: The aim of our study was to evaluate the efficacy of magnetic resonance imaging (MRI) in the differential diagnosis between active myocarditis and myocardial infarction in patients with clinical symptoms mimicking acute myocardial infarction. MATERIALS AND METHODS: Between 1 January 2006 and 30 June 2007, 23 consecutive patients (21 men and 2 women) presenting with electrocardiographic abnormalities mimicking acute myocardial infarction and a clinical suspicion of acute myocarditis (fever, chest pain and elevated troponin levels) underwent contrast-enhanced cardiac MRI within a week of admission. All patients also underwent coronary angiography, which demonstrated the absence of significant coronary artery lesions. The mean follow-up period was 2+/-4 months. RESULTS: Cardiac MRI with injection of contrast material showed late subepicardial and intramyocardial enhancement in all patients. Subendocardial late enhancement, a typical pattern of myocardial infarction, was never seen. In addition, in agreement with the literature, there was prevalent involvement of the lateral segments of the left ventricular wall. CONCLUSIONS: Cardiac MRI could be a valuable tool for the early diagnosis of acute myocarditis, as it can demonstrate specific patterns that help rule out acute myocardial infarction.

Doppler myocardial imaging in patients with heart failure receiving biventricular pacing treatment.

BACKGROUND: In patients with heart failure, biventricular pacing (BIV) improves left ventricular (LV) performance by counteracting LV unsynchronized contraction caused by the presence of left bundle branch block (LBBB). However, no data are yet available on regional long-axis function in patients with LBBB or on BIV effectiveness in improving such a function in patients with heart failure and LBBB. METHODS AND RESULTS: We studied with standard 2D echocardiography and tissue Doppler imaging (TDI) 21 nonischemic patients in New York Heart Association (NYHA) class III-IV, with LBBB and QRS >/=120 ms, receiving BIV. To assess long-axis function, TDI qualitative analysis at the basal level of each LV wall was performed in M-mode color and pulsed wave Doppler modalities before and after BIV. By analysis of the interventricular septum, the inferior, posterior, lateral, and anterior walls, of 105 basal segments, the following electromechanical patterns were identified: normal (pattern I), mildly unsynchronized (pattern IIA), severely unsynchronized (pattern IIB), reversed early in systole (pattern IIIA), reversed late in systole (pattern IIIB), and reversed throughout all the systole (pattern IV). After BIV, (1) 49 (46.7%) of 105 segments showed unsynchronized contraction of the same degree as before; (2) 36 (34.3%) of 105 and 20 (19%) of 105 showed unsynchronized contraction of lesser and greater degree, respectively, than before; and (3) a preexcitation pattern was found in 11 (10.5%) of 105, but no segment with pattern IV was observed. According to TDI analysis, patients were divided into group 1 (10 of 21), with less severe LV asynchrony than before BIV, and group 2 (11 of 21), with no change or more severe LV asynchrony than before BIV. In group 1, (1) the LV ejection fraction increased significantly (P =.01); (2) the exercise tolerance, expressed as time and work capacity on the bicycle stress testing, increased significantly (P =.01, P =.003, respectively); (3) the 6-minute walked distance increased significantly (P =.01); and (4) the NYHA class decreased significantly (P =.003). In group 2, no significant differences were found either in LV ejection fraction, in NYHA class, or in exercise tolerance data (P = not significant for all). Conversely, the QRS narrowing was significant in both groups (P =.003 in group 1 and P =.01 in group 2). CONCLUSIONS: TDI is useful in assessing the severity of LV asynchrony in patients with LBBB with heart failure as well as in evaluating the pacing effects on long-axis function in these patients. BIV reduced unsynchronized and/or dyskinetic contraction in at least one third of the LV basal segments, whereas it induced preexcitation in approximately 10%. Such changes were responsible for better LV synchrony in approximately one half of patients. After BIV, LV performance improved significantly in patients with better LV synchrony evaluated by TDI, whereas the QRS narrowing was not predictive of this functional improvement.

Electrotherapeutic management of patients with heart failure.

Heart failure is associated with poor long term survival due to progressive refractory heart dysfunction and sudden cardiac death. Cardiac resynchronization through atrio-biventricular pacing has been introduced to treat patients affected by drug-refractory heart failure with desynchronized ventricular activation, as for complete left bundle branch block. The technique is aimed to overcome interventricular and intraventricular conduction delays leading to ventricular dysynchrony, paradoxical septal wall motion, presystolic mitral regurgitation and reduced diastolic filling times. Short term studies demonstrated that biventricular pacing (and perhaps left ventricular pacing alone) may improve both systolic and diastolic function. Initial studies in patients receiving long term pacing consistently showed significant QRS shortening associated with improvement in symptoms, left ventricular ejection fraction, exercise tolerance, quality of life and New York Heart Association functional class. As far as sudden cardiac death prevention in heart failure is concerned, implantable cardioverter defibrillator (ICD) implantation has been demonstrated to be the most effective therapy in patients with prior cardiac arrest due to ventricular fibrillation or poorly tolerated ventricular tachycardia. Low left ventricular ejection fraction, unsustained ventricular tachycardia and inducibility at electrophysiological study also may identify high risk patients requiring ICD implantation. Further studies are needed to evaluate the effect of cardiac resynchronization on hard end-points, such as survival and long term clinical outcome, and to upgrade risk stratification criteria to be used in selection of candidates for ICD implantation.

[Indications and potential benefits of implantable automatic defibrillator endowed with biventricular pacing]. / Indicazioni e potenziali benefici dell'impianto di un defibrillatore automatico dotato di stimolazione biventricolare.

Heart failure (HF) is associated with a poor long-term survival due to progressive refractory heart dysfunction and sudden cardiac death. Cardiac resynchronization through three-chambered atriobiventricular pacing has been introduced to treat patients with drug-refractory HF and unsynchronized ventricular activation due to left bundle branch block (LBBB). The technique is aimed to overcome inter- and intraventricular conduction delays leading to a ventricular dyssynchrony, characterized by paradoxical septal wall motion, presystolic mitral regurgitation, and reduction in diastolic filling times. Acute studies demonstrated that biventricular pacing (and maybe left ventricular pacing alone) may improve both systolic and diastolic function. First studies on chronically paced patients consistently showed that the QRS shortening was associated with a significant improvement in symptoms, NYHA functional class, left ventricular ejection fraction (LVEF), exercise tolerance, and quality of life. As far as sudden cardiac death prevention in HF is concerned, the implantable cardioverter-defibrillator (ICD) has been demonstrated to be the most effective therapy in patients with prior cardiac arrest due to ventricular fibrillation or poorly tolerated ventricular tachycardia. Low LVEF, unsustained ventricular tachycardia and inducibility at electrophysiological study also may identify high risk patients requiring ICD implantation. Further studies are needed in evaluating the impact of cardiac resynchronization on hard endpoints, such as survival and long-term clinical outcome, as well as in upgrading risk stratification criteria to be used in candidate selection to ICD implantation. However, HF patients with prior cardiac arrest and LBBB should be considered as the optimal candidates to the "ICD implantation combined with biventricular pacing". Conversely, HF patients with LBBB, but without cardiac arrest, could be considered for "biventricular pacing combined with an ICD". The selection criteria for this novel non-pharmacological therapy still have to be defined. The authors emphasize the main indication to ICD implantation combined with biventricular pacing, i.e. HF patients with prior cardiac arrest and LBBB; controversially, while they discuss the other indications to biventricular pacing combined with an ICD.

Multisite stimulation in refractory heart failure.

Since the early nineties, the employment of DDD pacing from a right ventricular site with a short AV delay in patients with severe heart failure has led to considerable conflicting results, so that the real benefit of this method remains to be defined even in selected patients, such as those with first-degree AV block, QRS duration > 140 ms due to left bundle branch block (LBBB), mitral regurgitation time > or = 450 ms and diastolic filling time < or = 200 ms. Indeed, the asynchronous activation induced by pacing the right apex is the most important limitation to the technique, particularly in patients without an LBBB pattern or in those with an incomplete LBBB pattern. Recent studies have also shown that pacing of the right interventricular septum provides no better results than pacing of the right apex, at least in selected patients with no LBBB pattern and no significant mitral regurgitation. Today, it has been suggested that permanent biventricular pacing could be proposed as a feasible and reliable approach to improving ventricular function through the synchronization of the septum and the apex of the left ventricle, particularly in patients with a marked delay in ventricular activation sequence. This technique may be performed by means of transvenous leads inserted through the coronary sinus into the cardiac veins to stimulate both ventricles simultaneously, starting from the right apex and left lateral wall. Consequently, this approach supplies a strong basis for initiating further studies to examine the chronic effects of left ventricular pacing in patients with severe heart failure. We also suggest that the new tissue Doppler imaging techniques could usefully be applied to accurately select candidates to biventricular pacing.

Lack of correlation between ventricular late potentials and left ventricular mass in top-level male athletes.

PURPOSE: The aim of this study was to establish: 1) the prevalence of abnormal signal-averaged electrocardiogram (SAECG) in a large population of top-level athletes and 2) the relationship between SAECG parameters and left ventricular mass. One-hundred and fifty-three elite male athletes without apparent heart disease, symptoms, or arrhythmias were studied. METHODS: Fifty-six athletes (37%) had increased left ventricular mass (> 134 g.m(-2)). All athletes underwent time-domain SAECG on 300-400 heart beats recorded at rest from three bipolar orthogonal tests with a filter setting of 40-250 Hz. Criteria for abnormality were 1) filtered QRS duration > 114 ms, 2) duration of low-amplitude signals > 38 ms, or 3) root mean square voltage of the last 40 ms of the filtered QRS < 20 microV. RESULTS: The prevalence of abnormal SAECG was 7.2% (abnormality of one parameter), 6.5% (abnormality of two parameters), and 5.8%(abnormality of three parameters). The prevalence of abnormal SAECG was similar in athletes with or without increased left ventricular mass. CONCLUSIONS: In conclusion, this study showed: 1) the low rate of positive results of SAECG parameters in top-level male athletes, similar to that found in healthy sedentary subjects; and 2) the lack of correlation between left ventricular mass and overall SAECG parameters.

[The stratification and prevention of the arrhythmia risk in nonischemic dilated cardiomyopathy]. / Stratificazione e prevenzione del rischio aritmico nella cardiomiopatia dilatativa non ischemica.

The challenge of preventing arrhythmic sudden death is one of the major issues in today's treatment of heart failure. To achieve this ambitious goal, an accurate selection of the candidates for sudden death is needed on the one hand, while on the other hand, the assessment of the real cost/benefit ratio of the implantable cardioverter-defibrillator in selected patients, as compared to ACE inhibitors, beta-blockers and antiarrhythmic drug therapy, should no longer be delayed. As is well known, the incidence of sudden death is higher in ischemic dilated cardiomyopathy than it is in non-ischemic dilated cardiomyopathy. Moreover, tachyarrhythmic sudden death is prevalent in NYHA classes I and II (80%), whereas its incidence is lower (50%) in NYHA classes III and IV, since bradyarrhythmia, electromechanical dissociation and thromboembolic events characterize the other 50% of sudden deaths in patients in the latter NYHA class. The stratification of arrhythmic risk in non-ischemic dilated cardiomyopathy is questionable from any point of view, considering the poor predictive power of invasive and non-invasive indexes. However, some subgroups of high-risk patients should be selected, such as patients waiting for heart transplant or those with a severe disease but without an extreme degree of ventricular dysfunction, in whom the prognosis in terms of pump failure events is better and life expectancy is longer if the risk of arrhythmia is properly assessed and sudden death prevented. Consequently, the ICD implant may be effective in order to pursue the aim of reducing the tachyarrhythmic and bradyarrhythmic mortality in patients with a more severe disease and of minimizing the tachyarrhythmic risk in those with a less severe disease. Further studies will be developed to identify the ideal candidates for ICD implants.

Indications for dual-chamber (DDD) pacing in implantable cardioverter-defibrillator patients.

New technologic development of implantable cardioverter-defibrillators (ICDs) keeps up with the exponential increase of their use for primary and secondary prevention of sudden cardiac death. The first-generation ICD with limited shock capability alone could be considered adequate in most cardiac arrest victims, but it was not suitable for sudden death prevention in all high-risk patients with cardiac disease. The second-generation ICD was comprised of hybrid pacemaker-defibrillator systems that provided on-demand ventricular antibradycardia pacing. The third-generation devices include additional functions, such as antitachycardia pacing for ventricular tachycardia (VT) reversion and low-energy ventricular cardioversion, in addition to ventricular defibrillation and single-chamber ventricular demand pacing. In the near future, advanced dual-chamber atrioventricular (AV) pacing and defibrillating systems will also be available. The dual chamber ICD will allow atrial inhibited/dual-chamber (AAI/DDD) rate-responsive pacing, simultaneous atrial and ventricular sensing to optimize the arrhythmia identification, and ICD shock delivery in the proper arrhythmia-related chamber. Clinical benefits of these devices compared with their cost and complexity will require careful evaluation.

Ventricular arrhythmias and athlete's heart. Role of signal-averaged electrocardiography.

The aim of this study was to assess the prevalence and the prognostic value of ventricular late potentials in apparently healthy top-level athletes with ventricular arrhythmias, and the effect of physiological myocardial hypertrophy (athlete's heart) on the electrogenesis of the signal-averaged electrocardiogram (ECG). Two groups of asymptomatic athletes without underlying heart disease were studied: group A consisted of 35 athletes without arrhythmias and group B of 25 athletes with frequent and complex ventricular arrhythmias (ventricular ectopic beats > 5000.24 h-1 and ventricular couplets > 15.24 h-1). Late potentials were present if athletes had significantly prolonged filtered QRS and low amplitude signal duration and low root mean square voltages at both 25-250 Hz and 40-250 Hz filters. While late potentials were absent in all normal athletes of group A, they were present in seven of 25 (28%) athletes with arrhythmias of group B (P < 0.003). Ten of 25 athletes (five with and five without late potentials) of group B underwent programmed ventricular stimulation using a protocol comprising up to three extrastimuli. No episode of sustained ventricular tachycardia was induced. In four of five athletes with late potentials and in one of five without them, unsustained ventricular responses were induced. Echocardiographically determined left ventricular mass found in both groups of athletes did not influence the pathological result of the signal-averaged ECG parameters. This study shows the applicability of the signal-averaged ECG in identifying ventricular late potentials in a selected population of top-level athletes with frequent and complex ventricular arrhythmias and without overt heart disease; it also shows that the presence of late potentials is not influenced by left ventricular mass, even if extreme ( > 350 g), and it is correlated to a non-sustained ventricular response during an electrophysiological study.

[Heart failure and arrhythmias: the role of ACE inhibitors]. / Insufficienza cardiaca e aritmie: ruolo degli ACE-inibitori.

Mortality of patients with congestive heart failure (CHF) is high; > 40% of deaths are sudden, most often due to sustained ventricular arrhythmias (VA). In such patients frequent ventricular premature beats (VPB) and non sustained ventricular tachycardia (NSVT) are common. The relationship between VA and an increased risk for sudden death has been reported for patients with recent myocardial infarction. Although such relationship is uncertain for patients affected by dilated cardiomyopathy, many authors have reported an association between the frequency and the complexity of VA and the risk of sudden death. Many factors are responsible for VA in CHF: structural abnormalities, electrolyte imbalance, hemodynamic impairment, pharmacologic therapy and abnormal activation of neurohormonal system. ACE inhibitors have reduced VA in several experimental models, suggesting that these drugs decrease heart vulnerability to arrhythmogenic stimuli such as reperfusion and electrical stimulation. Many clinical trials have demonstrated that ACE inhibitors decreased VPB frequency and the prevalence of NSVT. Although ACE inhibitors decrease VA frequency, the reduction in cardiac mortality observed in CONSENSUS31 and in SOLVD32 trials was due only to a decrease in the progression of CHF. Recently the results of V-HeFT II33 trial have shown that the reduction in VA prevalence observed in patients treated with enalapril paralleled a reduction of sudden death. Factors that may contribute to the reduction in VA by ACE inhibitors include: increase in serum potassium; unloading of the ventricle; decrease in myocardial oxygen consumption. However, the most important factor seems related to their interference on neurohormonal system whose abnormal activation is the main mechanism of CHF progression.

Relation of prognosis in sick sinus syndrome to age, conduction defects and modes of permanent cardiac pacing.

A large population of sick sinus syndrome (SSS) patients was analyzed to determine whether age of patients, presence of conduction disturbances and mode of permanent pacing are related to the occurrence of supraventricular tachyarrhythmias, cerebral embolism and cardiac mortality. Three hundred thirty-nine patients permanently paced (135 AAI, 79 DDD, 125 VVI) because of SSS were followed for a mean period of 5 years (range 2 to 10). Patients were divided into 4 groups according to age (less than 70 or greater than 70 years) and the presence or absence of an associated conduction disturbance. Sixty-eight percent of VVI, 55% of AAI and 40.5% of DDD patients were greater than 70 years of age. In the VVI and DDD groups a conduction disturbance was present in 67 of 204 (33%) patients; conduction disturbances were more common in patients greater than 70 years old (46 of 111, 41%) than in those less than 70 years old (21 of 93,22%). The Wenckebach threshold (greater than 140 beats/min) remained unchanged during the follow-up period in 82% of AAI patients. In 9% of these patients, the Wenckebach threshold showed some degree of deterioration, but only in 2 patients was it less than 100 beats/min (1.5%). Spontaneous second-degree atrioventricular block was observed in 7 patients (5%); it disappeared in 6 of these patients when drug therapy was discontinued.(ABSTRACT TRUNCATED AT 250 WORDS)

[Endocavitary transcatheter electric fulguration as a therapeutic alternative in refractory ventricular tachycardia]. / La folgorazione elettrica endocavitaria transcatetere quale alternativa terapeutica della tachicardia ventricolare refrattaria.

Three patients affected by dilated cardiomyopathy complicated by refractory ventricular tachycardia, with a high risk of sudden cardiac death, underwent transcatheter electric fulguration. The technique was applied transeptally, using the terminals of two catheter electrodes as cathode and anode. These were placed at the right and left ventricular apex, at septal level where the "critical" arrhythmia point had been identified by endocardial mapping. All patients had previously experienced more than one episode of cardiac arrest and had successfully taken several antiarrhythmic drugs. All patients presented variable morphology of ventricular tachycardia (whether spontaneous or induced). In all of them clinical tachycardia was considered as having a left bundle branch block morphology with an earlier activation at low septal level. After treatment, antiarrhythmic therapy (amiodarone 200 mg/day) was continued for all patients, although at a lower dose than before fulguration. One patient has been free from sustained ventricular tachycardia for more than two years after fulguration. In the other patients we observed an early and late arrhythmic recurrence (respectively within 1 and 8 months following fulguration) in spite of antiarrhythmic therapy. The second patient presented no further recurrence after permanent pacemaker implantation. The third patient showed an arrhythmic recurrence, with a different morphology from the previous one, concomitantly with a septic process. This technique does not appear dangerous and may be used, in highly specialized centres, on carefully selected patients as a therapeutic approach after pharmacological therapy and before automatic defibrillator implantation or surgical antiarrhythmic intervention.

Multiform ventricular ectopic rhythm by combined parasystolic and reentrant activities.

Multiform ventricular ectopic rhythm (MVER), i.e., at least two QRS configurations of ventricular ectopic beats (VEBs), was assessed by 24-hour ambulatory ECG recording in four patients with ventricular parasystole (VP). In two of these four patients, VEBs with fixed coupling to the preceding impulses coexisted with VP beats of different configuration. In case no. 1, the VEBs had an identical coupling interval to sinus beats and VP beats, suggesting a mechanism of reentry elicited from both dominant pacemakers. In case no. 2, an intermittent form of VP due to type II second-degree entrance block was present. In this patient, the VEBs were coupled to sinus beats and to sinus-VP fusion beats and appeared to be dependent on the sinus beats reaching the VP focus. A mechanism of reentry determined by the penetration of sinus beats into the VP area, with prematurity-dependent aberrancy of VEBs, was suggested for the coupled VEBs in this patient. These observations suggest that the coexistence of an automatic ventricular ectopic focus and of a reentrant activity determined by, or elicited from, an area of automaticity may constitute the underlying mechanism of MVER in some patients.

Oral nifedipine in the long-term management of severe chronic heart failure.

We evaluated the hemodynamic effects of nifedipine in 10 symptomatic patients with chronic refractory heart failure due to idiopathic cardiomyopathy. Nifedipine significantly increased cardiac index (from 1.80 +/- 0.4 to 3 +/- 0.6 L/min/m2), stroke volume index (from 21 +/- 6 to 33 +/- 8 ml/beat/m2), and stroke work index (from 17.9 +/- 7 to 25.5 +/- 7 g-m/m2). The drugs also produced a significant decrease in left ventricular filling pressure (from 24.6 +/- 3 to 19 +/- 2 mm Hg), mean blood pressure (from 86 +/- 9 to 74 +/- 5 mm Hg), mean pulmonary arterial pressure (from 31.9 +/- 5 to 25.6 +/- 3 mm Hg), total systemic vascular resistance (from 2,104 +/- 329 to 1,088 +/- 249 dyn/s/cm-5), and pulmonary vascular resistance (from 200 +/- 71 to 107 +/- 50 dyn/s/cm-5). Heart rate remained unchanged. In all patients maintained on nifedipine therapy, repeat hemodynamic studies at 2 months revealed sustained effects, and all patients had symptomatic improvement of at least one New York Heart Association (NYHA) functional class. Long-term treatment was well tolerated. Forty-eight hours after discontinuation of nifedipine administration the hemodynamic benefits were lost. We conclude that nifedipine may be of value for long-term ambulatory therapy of severe chronic heart failure.