Physiopathologic correlates of intrathoracic impedance in chronic heart failure patients.

BACKGROUND: Increased plasma levels of amino-terminal fraction of brain natriuretic peptide (NT-proBNP) and alterations of diastolic filling as described by Doppler transmitral flow pattern are well-known markers of decompensated heart failure (HF). Recently, some implantable defibrillators have allowed monitoring of intrathoracic impedance, which is related to lung water content, potentially indicating HF deterioration. The aim of this study was to assess the correlation between intrathoracic impedance and NT-proBNP and echo-Doppler transmitral flow indexes. METHODS: Data were collected from 111 HF patients, in six Italian centers. All patients were on optimal medical therapy. Device diagnostics, echographic data, NT-proBNP determination, and clinical status as assessed by the Heart Failure Score (HFS) were registered at baseline, at bimonthly visits, and at unscheduled examinations due to HF decompensation or device alerts. RESULTS: Over a median follow-up of 413 days, 955 examinations were performed. Intrathoracic impedance was significantly correlated with NT-proBNP (P = 0.013) and with mitral E-wave deceleration time (DtE) (P = 0.017), but not with HFS. At the time of confirmed alert events, NT-proBNP was significantly higher than during confirmed nonalert event examinations; DtE did not differ, whereas impedance was significantly lower. CONCLUSION: A decrease in intrathoracic impedance is inversely correlated with NT-proBNP and directly correlated with DtE. Intrathoracic impedance monitoring therefore has the physiologic basis for being a useful tool to identify early HF decompensation.

Radiofrequency ablation of drug-refractory atrial fibrillation: an observational study comparing 'ablate and pace' with pulmonary vein isolation.

AIMS: To compare clinical characteristics, procedure complexity, acute and long-term outcome of 'ablate and pace' (A&P) with pulmonary vein isolation (PVI) in patients with drug-refractory atrial fibrillation (AF). So far, only few small studies have compared the two procedures. METHODS AND RESULTS: We analysed retrospectively a cohort of symptomatic consecutive patients with drug-refractory AF. Group 1 included 100 patients treated with A&P and Group 2 included 144 patients treated with PVI. Group 1 patients were older (74 +/- 8 vs. 56 +/- 9 years; P < 0.0001), had lower left ventricular ejection fraction (50 +/- 13% vs. 59 +/- 7%; P < 0.05), and a lower prevalence of paroxysmal AF (46% vs. 65%; P < 0.05). Acute success was not statistically different (98% vs. 92.3%, P = ns). Group 1 patients had shorter procedure time and lower radiation exposure with respect to Group 2 patients (70 +/- 15 vs. 204 +/- 58 min, and 8 +/- 4 vs. 57 +/- 22 min; P < 0.0001, respectively). After a median follow-up of 29 months (I, III quartile; 15, 40 months) vs. 25 months (I, III quartile; 8, 36 months) (P = ns), all the patients in Group 1 were free of symptomatic AF, while 113 patients (79%) of Group 2 were in stable sinus rhythm (P < 0.0001). Persistent or permanent AF has been documented in 58 patients (58%) of Group 1 vs. 11 (8%) of Group 2 (P < 0.0001). CONCLUSION: In this series (i) patients treated with A&P and PVI for drug-refractory AF showed significant differences in clinical profile; (ii) A&P is a shorter and less complex procedure, but is associated with a higher rate of persistent AF; (iii) symptomatic recurrences of paroxysmal AF were more frequent in PVI group. Randomized studies appear necessary to identify the best strategy in selected cases.

Effects of cardiac resynchronization therapy on disease progression in patients with congestive heart failure.

BACKGROUND: Cardiac resynchronization therapy (CRT) represents a new therapeutic modality of proven efficacy for selected patients with heart failure and ventricular asynchrony. The aim of this study was to assess the effects of CRT on clinical variables and cardiac remodeling in patients with moderate-to-severe congestive heart failure and inter/intraventricular conduction delays. METHODS: Thirty-seven patients (32 males, 5 females, mean age 73 +/- 7 years), in NYHA functional class III-IV, with left ventricular ejection fraction (LVEF) < or = 35%, QRS > or = 150 ms, and left ventricular end-diastolic diameter (LVEDD) > or = 55 mm, underwent CRT by biventricular pacing (InSync, InSync III, InSync ICD; Medtronic Inc.). Fourteen (37.8%) had a previous pacemaker, and 11 (29.7%) were in permanent atrial fibrillation. The QRS width, NYHA functional class, LVEDD, left ventricular end-systolic diameter (LVESD), left ventricular end-diastolic volume (LVEDV), left ventricular endsystolic volume (LVESV), and LVEF were retrospectively evaluated in the period before CRT. For the purposes of the present study, the pre-CRT period was divided in two: T(-2) (from 6 to 3 years) and T(-1) (from 3 years to CRT). Moreover, these parameters were measured at the time of CRT (T0) and prospectively in the post-CRT follow-up (Tp). RESULTS: Before CRT, a progressive worsening of the parameters was observed. The QRS duration steadily increased from T(-2) to T(-1) and T0 (both p = 0.000). The NYHA functional class increased from T(-2) to T(-1) and T0 (both p = 0.000). LVEDD and LVESD also increased and were higher at T(-1) (p = 0.001 and p = 0.000, respectively) and at T0 (both p = 0.000) compared to T(-2). Similar results were observed for LVEDV and LVESV. Finally, LVEF was higher at T(-2) than T(-1) and T0 (both p = 0.000). After CRT, there was a reduction in the QRS duration and an improvement in the NYHA functional class compared to T0 (both p = 0.000). LVEDD and LVESD were also reduced (p = 0.005 and p = 0.016, respectively), LVEDV and LVESV decreased (both p = 0.000), and LVEF increased (p = 0.000) with respect to T0. A highly significant correlation was found between LVEDD and LVESD both in the pre- and post-CRT time intervals, with a non-significant difference between the two linear regression lines. Similar results were obtained for the correlations between LVEDV and LVESV. CONCLUSIONS: Congestive heart failure is associated with a progressive widening of the QRS complex and a worsening of the clinical status and results in anatomic remodeling with deterioration of the left ventricular function. CRT induces opposite changes in QRS duration, clinical status, and left ventricular remodelling.

Chemotherapy-related cardiotoxicity: new diagnostic and preventive strategies.

Chemotherapy is an established approach for several malignancies, but its utility may be hampered by induced cardiac toxicity possibly leading to heart failure, with a negative impact on the patient's quality of life and ultimately survival. Prospective left ventricular systolic function monitoring has demonstrated that cardiotoxicity could be subclinically present for many months or years before its overt manifestation. Although considered irreversible, some reports suggested recovery or delayed progression of cardiac dysfunction by preventive cardioactive therapies. Thus, the identification of earlier instrumental or biochemical markers of cardiac injury able to predict heart failure remains a major task. Diastolic indexes as a primary expression of hemodynamic dysfunction after cardiac damage, analyzed by means of conventional or newer Doppler technologies (tissue Doppler, color M-mode, etc.) are discussed. Moreover, brain natriuretic peptides, troponins and endothelin-1, as possible sensitive/specific markers/predictors of subclinical cardiotoxicity are reviewed in order to update and possibly improve the strategy for the detection and clinical management of chemotherapy-related cardiotoxic effects.

Efficacy and safety of catheter ablation versus antiarrhythmic drugs for atrial fibrillation: a meta-analysis of randomized trials.

BACKGROUND: Atrial fibrillation is the most common arrhythmia in clinical practice. Its treatment is still widely debated due to the large variety of therapeutic options. Radiofrequency catheter ablation (RFCA) around pulmonary vein ostia and in the left atrium has been proposed as a technique to cure atrial fibrillation and is now performed with increasing success worldwide. However, few randomized controlled trials (RCTs) are available. Some of these have been published recently and are not yet included in meta-analyses. OBJECTIVES: We conducted a meta-analysis to summarize the current evidence base for the efficacy and safety of RFCA in patients with atrial fibrillation. METHODS: We searched electronic databases for relevant RCTs comparing RFCA with antiarrhythmic drugs for the management of atrial fibrillation. Recurrence of any atrial tachyarrhythmia (including atrial fibrillation, atrial flutter and atrial tachycardia) and rate of complications and adverse events were the end-points of the analysis. The results are reported as relative risk and 95% confidence interval, calculated using RevMan 5. RESULTS: A total of eight RCTs were identified including 844 patients. Overall, 98 (23.2%) of 421 patients in the treatment group and 324 (76.6%) of 423 patients in the control group had atrial tachyarrhythmia recurrence. RFCA decreased atrial tachyarrhythmia recurrence by 71% (relative risk 0.29, 95% confidence interval 0.20-0.41, P < 0.00001, with random effects model). Fewer complications and adverse events were reported in the ablation group compared with the control group (relative risk 0.72, 95% confidence interval 0.40-1.30, P = 0.28, with random effects model). CONCLUSION: In selected patients with atrial fibrillation, RFCA is a relatively effective and well-tolerated procedure to cure atrial fibrillation. Even though the results of our systematic review favour ablation therapy, large, well-designed RCTs are needed to confirm the efficacy and safety of RFCA for the management of atrial fibrillation.

Acute haemodynamic effects of intra-aortic balloon pump and cardiac resynchronization therapy.

We report two cases in which intra-aortic balloon pump (IABP) was used successfully as a bridge to cardiac resynchronization therapy (CRT) to treat patients with refractory systolic heart failure. The study was designed to assess the acute haemodynamic effects of IABP coupled with CRT using standard haemodynamic monitoring. In both cases, a marked elevation of V-wave in pulmonary capillary wedge pressure (PCWP) was shown, and a moderate-to-severe functional mitral regurgitation was observed. IABP and CRT resulted in a significant acute improvement in aortic pressure, PCWP, and V-wave amplitude compared with baseline measurements and IABP alone. These results provide a basis for studies examining the haemodynamic effects of IABP support associated with CRT in patients with heart failure refractory to medical therapy.

Volume overload modulates effects of cardiac resynchronization therapy independently of myocardial reperfusion: results of the RESYNC study.

OBJECTIVES: Cardiac resynchronization therapy (CRT) may induce significant changes in regional wall motion and perfusion. However, the link between these variables in patients with heart failure has not been investigated. METHODS: Thirty-six patients with idiopathic (n = 22) or ischemic (n = 14) cardiomyopathy (mean age 70 +/- 8 years, 24 male) were studied by echocardiography and gated single-photon emission computed tomography (SPECT) before and within 2 months after CRT. RESULTS: New York Heart Association class improved in all but four patients. The perfusion analysis indicated that, in all but three patients, there was a significant improvement of tracer uptake. Baseline end-diastolic volume index obtained by gated SPECT modulated increase of ejection fraction (P < 0.001), reduction of end-systolic volume index (P < 0.01) and improvement of motion (P < 0.001), as well as of left ventricular wall thickening (P < 0.002). Finally, despite CRT inducing significant reperfusion independently of volume overload (P < 0.05), extension of perfusion defect correlated with global improvement in the follow-up (P < 0.05). CONCLUSIONS: Volume overload may identify responders to resynchronization therapy. CRT induced a significant 'reperfusion' both in ischemic and idiopathic cardiomyopathies, even if this is not sufficient to improve left ventricular function in patients with more severe volume overload. Finally, simultaneous evaluation of volume overload and perfusion defects may result useful in identifying CRT responders.

Treatment of macro-re-entrant atrial tachycardia based on electroanatomic mapping: identification and ablation of the mid-diastolic isthmus.

AIMS: This multicentre prospective study evaluated the ability of electroanatomic mapping (EAM) using a specific parameter setting to identify clearly the mid-diastolically activated isthmus (MDAI) and guide ablation of macro-re-entrant atrial tachycardia (MAT). METHODS AND RESULTS: Consecutive patients with MAT, different from typical isthmus-dependent atrial flutter, were enrolled. EAM was performed using a specific setting of the window of interest, calculated to identify the MDAI and guide ablation of this area. Sixty-five patients exhibiting 81 MATs (mean cycle length 308 +/- 68 ms) were considered. Thirty-two (49.2%) had previous heart surgery. In 79 of 81 morphologies (97.5%), EAM reconstructed 95.9 +/- 4.3% of the tachycardia circuit and identified the MDAI; 23 of the 79 morphologies (29.1%) were double-loop re-entry. Mapping of two morphologies was incomplete due to MAT termination after catheter bumping. In 73 of 79 mapped morphologies (92.4%), abolition of the MAT was obtained by 13.2 +/- 12.4 applications. During the 14 +/- 4 month follow-up, MAT recurred in 4 of the successfully treated patients (6.8%). CONCLUSION: EAM using a specific parameter setting proved highly effective at identifying the MDAI in MAT, even in patients with previous surgery and multiple re-entrant loops. Ablation of the MDAI yielded acute arrhythmia suppression with low rate of recurrence during follow-up.