Low atrial fibrillatory rate is associated with spontaneous conversion of recent-onset atrial fibrillation

AIMS

Atrial fibrillatory rate (AFR) is considered a non-invasive index of atrial remodelling. Low AFR has been associated with favourable outcome of interventions in patients with persistent atrial fibrillation (AF). However, AFR has never been studied in unselected patients with short duration of AF, prone to regain sinus rhythm (SR) spontaneously. The aim of the study was to assess if AFR can predict spontaneous conversion in patients with recent-onset AF.

METHODS AND RESULTS

Files of consecutive patients with AF < 48 h seeking emergency room care during a 12-month period were screened (n = 225). Patients with thyroid illness, acute ischaemic heart disease (IHD) or acute congestive heart failure, significant valvular heart disease, congenital heart disease, history of cardiac surgery or catheter ablation, or on class I/III antiarrhythmics were excluded. Atrial fibrillatory rate was obtained by QRST cancellation and time frequency analysis of electrocardiogram at admission. The study population comprised 148 patients (age 64 ± 13 years, 52 men), of whom 48 converted to SR within 18 h. Those converting spontaneously comprised more women, had a higher prevalence of first-ever AF episode, IHD, and a lower AFR. The multivariate analysis revealed: AFR < 350 fibrillations per minute [odds ratio (OR) 3.7, 95% confidence interval (CI) 1.3-10.5, P = 0.016], IHD (OR 5.7, 95% CI 1.5-22.4, P = 0.012) and first-ever AF episode (OR 4.1, 95% CI 1.3-13.0, P = 0.015) as independent predictors of spontaneous conversion.

CONCLUSION

A low AFR was predictive of spontaneous conversion in patients with recent-onset AF. Along with first-ever AF episode and IHD, AFR can be used in assessing likelihood of spontaneous conversion, if proven in prospective studies.

Manual correction of semi-automatic three-dimensional echocardiography is needed for right ventricular assessment in adults; validation with cardiac magnetic resonance

BACKGROUND

Three-dimensional echocardiography (3DE) and semi-automatic right ventricular delineation has been proposed as an appropriate method for right ventricle (RV) evaluation. We aimed to examine how manual correction of semi-automatic delineation influences the accuracy of 3DE for RV volumes and function in a clinical adult setting using cardiac magnetic resonance (CMR) as the reference method. We also examined the feasibility of RV visualization with 3DE.

METHODS

62 non-selected patients were examined with 3DE (Sonos 7500 and iE33) and with CMR (1.5T). Endocardial RV contours of 3DE-images were semi-automatically assessed and manually corrected in all patients. End-diastolic (EDV), end-systolic (ESV) volumes, stroke volume (SV) and ejection fraction (EF) were computed.

RESULTS

53 patients (85%) had 3DE-images feasible for examination. Correlation coefficients and Bland Altman biases between 3DE with manual correction and CMR were r = 0.78, -22 ± 27 mL for EDV, r = 0.83, -7 ± 16 mL for ESV, r = 0.60, -12 ± 18 mL for SV and r = 0.60, -2 ± 8% for EF (p < 0.001 for all r-values). Without manual correction r-values were 0.77, 0.77, 0.70 and 0.49 for EDV, ESV, SV and EF, respectively (p < 0.001 for all r-values) and biases were larger for EDV, SV and EF (-32 ± 26 mL, -21 ± 15 mL and - 6 ± 9%, p ≤ 0.01 for all) compared to manual correction.

CONCLUSION

Manual correction of the 3DE semi-automatic RV delineation decreases the bias and is needed for acceptable clinical accuracy. 3DE is highly feasible for visualizing the RV in an adult clinical setting.

Bileaflet blood cysts on the mitral valve in an adult

Blood cysts within the heart are very rare entities in adults. The authors present possibly the first ever case in which blood cysts were found on both mitral valve leaflets. A 65-year-old woman was referred for transthoracic echocardiography because of vague chest discomfort. Transthoracic echocardiography displayed echo-free cysts on the tips of both mitral valve leaflets. Subsequent transesophageal echocardiography confirmed this finding. The blood cysts were successfully surgically removed.

Moderate mitral regurgitation in patients undergoing CABG--the MoMIC trial

BACKGROUND

The presence of mild to moderate ischemic mitral regurgitation (IMR) marks a significantly reduced long-term survival and increased hospitalizations due to heart-failure. However, it is common practice in many institutions to refrain from repairing the mitral valve in these patients. There are no available conclusive data to support this practice, and thus there is a need for an adequately powered randomized trial.

STUDY DESIGN

The Moderate Mitral Regurgitation In Patients Undergoing CABG (MoMIC) trial is the first international multi-center, large-scale study to clarify whether moderate IMR in CABG patients should be corrected. A total of 550 CABG patients with moderate IMR are to be randomized to treatment of either CABG alone or CABG plus mitral valve correction. The primary end point is a composite end point of mortality and rehospitalization for heart failure at five years. The inclusion and randomization of patients started in February 2008.

IMPLICATION

If correction of moderate IMR in CABG patients proves to be the superior strategy, most patients should be treated accordingly.

B-type natriuretic peptide as a predictor of postoperative heart failure after aortic valve replacement

OBJECTIVE

B-type natriuretic peptide (BNP) has been established as a biomarker for heart failure. The objective was to evaluate BNP measured on arrival in the intensive care unit (ICU) as a predictor for heart failure defined as need for inotropic support or IABP beyond 24 hours postoperatively after aortic valve replacement.

DESIGN

A prospective, observational study.

SETTING

A cardiothoracic surgery unit at a tertiary level hospital.

PARTICIPANTS

One hundred sixty-one patients undergoing aortic valve replacement.

MEASUREMENTS AND MAIN RESULTS

Two levels of BNP were evaluated: the median (BNP >133 pg/mL) and a cutoff (BNP >82 pg/mL) based on receiver-operating characteristic (ROC) analysis. Uni- and multivariate analysis were performed to identify predictors of postoperative heart failure. Patients with postoperative heart failure (n = 37) showed a more than 10-fold increase in 30-day mortality (8.1%, 3/37) compared with patients without postoperative heart failure (0.8%, 1/124) (p = 0.038). Elevated postoperative BNP levels were identified as an independent predictor of postoperative heart failure: BNP >82 pg/mL (p = 0.004) and BNP >133 pg/mL (p = 0.013). The area under the ROC curve for BNP as a predictor of postoperative heart failure was 0.69.

CONCLUSION

Postoperative heart failure after aortic valve replacement is still a very serious condition with increased early mortality. The results of the present study suggest that an elevated BNP level on arrival in the ICU is an independent predictor of postoperative heart failure after aortic valve replacement. In the authors' opinion, an increased BNP level on arrival in the ICU may support early diagnosis and allow optimal management of heart failure after aortic valve replacement.

Changes in clot lysis levels of reteplase and streptokinase following continuous wave ultrasound exposure, at ultrasound intensities following attenuation from the skull bone

Background

Ultrasound (US) has been used to enhance thrombolytic therapy in the treatment of stroke. Considerable attenuation of US intensity is however noted if US is applied over the temporal bone. The aim of this study was therefore to explore possible changes in the effect of thrombolytic drugs during low-intensity, high-frequency continuous-wave ultrasound (CW-US) exposure.

Methods

Clots were made from fresh venous blood drawn from healthy volunteers. Each clot was made from 1.4 ml blood and left to coagulate for 1 hour in a plastic test-tube. The thrombolytic drugs used were, 3600 IU streptokinase (SK) or 0.25 U reteplase (r-PA), which were mixed in 160 ml 0.9% NaCl solution. Continuous-wave US exposure was applied at a frequency of 1 MHz and intensities ranging from 0.0125 to 1.2 W/cm². For each thrombolytic drug (n = 2, SK and r-PA) and each intensity (n = 9) interventional clots (US-exposed, n = 6) were submerged in thrombolytic solution and exposed to CW-US while control clots (also submerged in thrombolytic solution, n = 6) were left unexposed to US.

To evaluate the effect on clot lysis, the haemoglobin (Hb) released from each clot was measured every 20 min for 1 hour (20, 40 and 60 min). The Hb content (mg) released was estimated by spectrophotometry at 540 nm. The difference in effect on clot lysis was expressed as the difference in the amount of Hb released between pairs of US-exposed clots and control clots. Statistical analysis was performed using Wilcoxon's signed rank test.

Results

Continuous-wave ultrasound significantly decreased the effects of SK at intensities of 0.9 and 1.2 W/cm² at all times (P < 0.05). Continuous-wave ultrasound significantly increased the effects of r-PA on clot lysis following 20 min exposure at 0.9 W/cm² and at 1.2 W/cm², following 40 min exposure at 0.3, 0.6, 0.9 and at 1.2 W/cm², and following 60 min of exposure at 0.05 0.3, 0.6, 0.9 and at 1.2 W/cm² (all P < 0.05).

Conclusion

Increasing intensities of CW-US exposure resulted in increased clot lysis of r-PA-treated blood clots, but decreased clot lysis of SK-treated clots.

The influence of patient-prosthesis mismatch on in-hospital complications and early mortality after aortic valve replacement

BACKGROUND AND AIM OF THE STUDY

The study aim was to analyze the relationship between patient-prosthesis mismatch (PPM) and in-hospital complications and mortality after aortic valve replacement (AVR).

METHODS

AVR was performed in 1,819 patients between January 1996 and July 2006. Follow up investigations were performed after a mean of 4.3 years (range: 0 days to 10.6 years). Univariate and multivariate analysis were used to evaluate risk factors for in-hospital complications and mortality in patients with prosthesis mismatch. Actuarial statistics were used to calculate survival rates.

RESULTS

Multivariate analysis showed that PPM (defined as indexed effective orifice area < or = 0.85 cm2/m2) was associated with an increased risk of postoperative neurological events (OR 2.26, 95% CI 1.05-4.83, p = 0.037). There were no significant differences in 30-day mortality between the PPM and non-PPM groups. Neither was any significant difference found between the two groups regarding long-term survival adjusted for significant risk factors for death after AVR.

CONCLUSION

The results suggest PPM to be an independent predictor of postoperative neurological complications in patients undergoing AVR. However, PPM did not negatively influence either short- or long-term survival. PPM may play an important role in selected categories of patients, and should be considered in order to avoid postoperative neurological complications.

Atrial fibrillatory rate and risk of left atrial thrombus in atrial fibrillation

AIMS

In atrial fibrillation (AF), a relation between electrocardiogram (ECG) fibrillatory wave amplitude and thrombus formation has been sought for long with conflicting results. In contrast, the possible relation between atrial fibrillatory rate obtained from the surface ECG and left atrial thrombus formation in patients with AF is unknown and was consequently evaluated in this study.

METHODS AND RESULTS

One-hundred and twenty-five patients (mean age 64 +/- 12 years, 72% male) with persistent non-valvular AF (mean duration 28 +/- 80 days) undergoing transesophageal echocardiography were studied. In all patients, standard 12-lead ECG recordings were acquired before the examination. Atrial fibrillatory rate was determined using spatiotemporal QRST cancellation and time-frequency analysis of lead V1. Atrial fibrillatory rate measured 401 +/- 63 fibrillations per minute (fpm, range 235-566 fpm) and was related with age (R = -0.326, P < 0.001), ventricular rate (R = -0.202, P = 0.024), gender (407 +/- 62 in males vs. 387 +/- 64 fpm in females, P = 0.038) but not AF duration (R = 0.088, P = 0.374), presence of lone AF (408 +/- 66 vs. 394 +/- 58 fpm, P = 0.228), or beta-blocker or calcium channel blocker treatment (398 +/- 63 vs. 405 +/- 62 fpm, P = 0.556). Age was the only independent predictor of fibrillatory rate (B = -1.714, P < 0.001). In patients with left atrial thrombus (n = 10), spontaneous echo contrast (SEC) was more frequently present (70 vs. 29 %, p = 0.007) and left atrial appendage (LAA) outflow velocity was lower (26 +/- 20 vs. 37 +/- 15 cm/s, P = 0.012) than in patients without thrombus (n = 115). In contrast, mean fibrillatory rate, which showed a weak inverse correlation with LAA velocity (R = -0.118, P = 0.048) was not different between both groups (380 +/- 56 vs. 403 +/- 63 fpm, P = 0.226). Similarly, presence of thrombus and SEC combined was not related with fibrillatory rate.

CONCLUSION

Atrial fibrillatory rate obtained from surface ECG lead V1 is not a risk marker for left atrial thrombus formation in AF.

Neurohumoral changes in patients with left ventricular dysfunction following acute myocardial infarction and the effect of nitrate therapy: a randomized, double-blind, placebo-controlled long-term study

BACKGROUND

Several neurohumoral mechanisms involved in cardiovascular regulation are activated in the failing heart, but only limited information is available regarding the influence of long-term nitrate therapy.

MATERIALS AND METHODS

This was a double-blind, randomized comparison of isosorbide-5-mononitrate (IS-5-MN), 60 mg given orally, once daily for 11 months to patients (n = 47) with left ventricular (LV) dysfunction following acute myocardial infarction (AMI). Forty-five patients received placebo. All patients received ramipril.Plasma natriuretic peptides (atrial [ANP] and brain [BNP] natriuretic peptide), epinephrine, norepinephrine (NEPI), antidiuretic hormone, aldosterone (Aldo), renin activity (PRA), substance P, neuropeptide Y-like immunoreactivity, calcitonin gene-related peptide, and vasoactive intestinal peptide were measured at baseline and at the end of the treatment period. Clinical, echocardiographic, and hemodynamic data were also obtained.

RESULTS AND CONCLUSIONS

Chronic nitrate therapy does not significantly affect the neurohumoral status in patients with LV dysfunction after AMI, apart from a decrease in ANP. Some hormones are more closely associated with diastolic dysfunction/increased volume load (ANP and BNP) and others are more closely associated with systolic dysfunction (PRA, NEPI, Aldo). There is a temporal dissociation of these 2 groups of hormones 1 year post infarction: ANP and BNP decrease, whereas NEPI and Aldo show a slight increase. BNP levels do not reflect all important pathophysiologic mechanisms in heart failure. Consequently, the use of other neurohormonal factors than BNP for monitoring of heart failure therapy should be explored.

Atrial fibrillation signal organization predicts sinus rhythm maintenance in patients undergoing cardioversion of atrial fibrillation

AIMS

Electrical remodelling is believed to influence the outcome following cardioversion of patients with persistent atrial fibrillation (AF). However, the results in clinical studies are conflicting. We assessed the hypothesis that non-invasively obtained atrial fibrillatory organization can be used as a predictor of sinus rhythm (SR) maintenance.

METHODS AND RESULTS

Fifty-four patients (37 men, age 67+/-11) with persistent AF (median duration 3 months, 1 day to 18 months), without anti-arrhythmic drug treatment, referred for cardioversion were studied. Assessment of the atrial harmonic decay was made by time-frequency analysis of the ECG. At 1-month follow-up, 30 patients had relapsed into AF. The mean harmonic decay at inclusion of those relapsing into AF was 1.5+/-0.3 compared with 1.1+/-0.3 among those maintaining SR (P=0.0004). Using a cut-off value of harmonic decay <or=1.5 to determine suitability for cardioversion would have resulted in a clinically useful discriminator (sensitivity=92%, specificity=47%, PPV=59%, and NPV=88%).

CONCLUSION

This study shows that patients relapsing rapidly to AF have a higher harmonic decay than those maintaining SR. The degree of AF signal organization (harmonic decay) was a superior discriminator to other patient parameters. Further studies are needed to confirm these results and to determine the electrophysiological correlate of harmonic decay.

Indices of Electrical and Contractile Remodeling During Atrial Fibrillation in Man

BACKGROUND

Atrial electrical and contractile remodeling have been demonstrated to coincide during atrial fibrillation (AF) in experimental studies. We explored whether electrical and contractile remodeling correlate in man and explored its clinical implications.

METHODS

Forty-nine patients with persistent AF were studied. Electrical remodeling was assessed noninvasively using spectral analysis to estimate the average fibrillatory rate (AFR). Atrial contractility was assessed by transesophageal echocardiography (TEE) measurement of left atrial appendage outflow velocity (LAAOV).

RESULTS

The AFR was 403+/-43 fibrillations per minute (fpm) and the LAAOV was 0.27+/-0.14 m/s. A significant correlation was found between AFR and LAAOV (r=-0.47, P=0.001). In patients with a LAAOV>or=0.25 m/s, the AFR was 387+/-48 fpm compared to 419+/-31 fpm among patients with LAAOV<0.25 m/s (P<0.01).

CONCLUSIONS

This study demonstrates that indices of electrical and contractile remodeling are strongly correlated in persistent AF in man. The interindividual overlap, however, is too large to allow predictions of LAAOV based on fibrillatory frequency alone.

Percutaneous treatment of ischaemic mitral regurgitation in sheep

AIMS

A percutaneous mitral annuloplasty device for implantation in the coronary sinus was evaluated in surviving sheep with ischaemia-induced mitral regurgitation.

METHODS AND RESULTS

Microspheres were injected in the left coronary artery of thirty-seven sheep. The treatment was repeated in one month intervals until the resulting myocardial infarctions caused significant mitral regurgitation. Fourteen animals developed a mitral regurgitation degree 2 or higher after 130+/-16 days and 3.4+/-0.4 treatments. The annuloplasty device was implanted percutaneously within the coronary sinus and the animals were followed 97+/-6 days (n=14) with monthly intracardiac echocardiograms. The MR grade (0-4) decreased from 3.1+/-0.2 at the time for implantation to 0.8+/-0.2 (p=0.0005) at the 3 month follow up. The vena contracta decreased from 6.5+/-0.4 mm to 2.0+/-0.7 mm after 3 months (p=0.0007). The mitral septo-lateral diameter was reduced after insertion of the device, from 38+/-1 mm before implantation to 35+/-1 mm after 3 months (P=0.0322). Angiography showed no signs of impairment of the coronary arteries. No thrombosis was observed.

CONCLUSION

These results indicate that experimentally induced ischaemic mitral regurgitation can be significantly reduced by means of a percutaneous catheter technique from the coronary sinus in surviving sheep.

Prediction of sinus rhythm maintenance following DC-cardioversion of persistent atrial fibrillation - the role of atrial cycle length

Background

Atrial electrical remodeling has been shown to influence the outcome the outcome following cardioversion of atrial fibrillation (AF) in experimental studies.

The aim of the present study was to find out whether a non-invasively measured atrial fibrillatory cycle length, alone or in combination with other non-invasive parameters, could predict sinus rhythm maintenance after cardioversion of AF.

Methods

Dominant atrial cycle length (DACL), a previously validated non-invasive index of atrial refractoriness, was measured from lead V1 and a unipolar oesophageal lead prior to cardioversion in 37 patients with persistent AF undergoing their first cardioversion.

Results

32 patients were successfully cardioverted to sinus rhythm. The mean DACL in the 22 patients who suffered recurrence of AF within 6 weeks was 152 ± 15 ms (V1) and 147 ± 14 ms (oesophagus) compared to 155 ± 17 ms (V1) and 151 ± 18 ms (oesophagus) in those maintaining sinus rhythm (NS). Left atrial diameter was 48 ± 4 mm and 44 ± 7 mm respectively (NS). The optimal parameter predicting maintenance of sinus rhythm after 6 weeks appeared to be the ratio of the lowest dominant atrial cycle length (oesophageal lead or V1) to left atrial diameter. This ratio was significantly higher in patients remaining in sinus rhythm (3.4 ± 0.6 vs. 3.1 ± 0.4 ms/mm respectively, p = 0.04).

Conclusion

In this study neither an index of atrial refractory period nor left atrial diameter alone were predictors of AF recurrence within the 6 weeks of follow-up. The ratio of the two (combining electrophysiological and anatomical measurements) only slightly improve the identification of patients at high risk of recurrence of persistent AF. Consequently, other ways to asses electrical remodeling and / or other variables besides electrical remodeling are involved in determining the outcome following cardioversion.

Percutaneous Transvenous Mitral Annuloplasty (PTMA) with the Viking device reduces pacing-induced mitral regurgitation

OBJECTIVES

The new percutaneous mitral annuloplasty Viking device was evaluated in surviving sheep with pacing-induced mitral regurgitation.

METHODS AND RESULTS

Twenty sheep were subjected to rapid ventricular pacing for one to three months, leading to cardiomyopathy and mitral regurgitation. Device implantation could be successfully performed in 11 of these animals after pacemaker treatment for 64+/-7 days. The device-related procedure time was 12+/-2 min. The mean follow-up time was 58+/-8 days after implantation of the device. Mitral annulus septo-lateral diameter was significantly reduced after insertion of the device, from 35+/-1 mm before implantation to 30+/-1 mm at the final follow up intracardiac echocardiography (P = 0.0097). The degree of mitral regurgitation (on a scale from 0 to 4) was 2.6+/-0.2 before device implantation and decreased to 0.8+/-0.2 after treatment (P = 0.0039), and the vena contracta was reduced from 7+/-0.4 mm to 3+/-0.8 mm (P = 0.0019). Angiography showed no signs of impairment of the coronary arteries. No thrombosis was observed.

CONCLUSIONS

These results indicate that the septo-lateral diameter of the mitral annulus, and the degree of experimentally induced mitral regurgitation, can be significantly reduced with a percutaneous catheter technique in surviving sheep.

Rapid fluctuations in atrial fibrillatory electrophysiology detected during controlled respiration

Heart rate during sinus rhythm is modulated through the autonomic nervous system, which generates short-term oscillations. The high-frequency components in these oscillations are associated with respiration, causing sinus arrhythmia, mediated by the parasympathetic nervous system. In this study, we evaluated whether slow, controlled respiration causes cyclic fluctuations in the frequency of the fibrillating atria. Eight patients (four women; median age 63 yr, range 53-68 yr) with chronic atrial fibrillation (AF) and third-degree atrioventricular block treated by permanent pacemaker were studied. ECG was recorded during baseline rest, during 0.125-Hz frequency controlled respiration, and finally during controlled respiration after full vagal blockade. We calculated fibrillatory frequency using frequency analysis of the fibrillatory ECG for overlapping 2.5-s segments; spectral analysis of the resulting frequency trend was performed to determine the spectrum of variations of fibrillatory frequency. Normalized spectral power at respiration frequency increased significantly during controlled respiration from 1.4 (0.76-2.0) (median and range) at baseline to 2.7 (1.2-5.8) (P = 0.01). After vagal blockade, the power at respiration frequency decreased to 1.2 (0.23-2.8) (P = 0.01). Controlled respiration causes cyclic fluctuations in the AF frequency in patients with long-duration AF. This phenomenon seems to be related to parasympathetic modulations of the AF refractory period.

Can pulsed ultrasound increase tissue damage during ischemia? A study of the effects of ultrasound on infarcted and non-infarcted myocardium in anesthetized pigs

BACKGROUND

The same mechanisms by which ultrasound enhances thrombolysis are described in connection with non-beneficial effects of ultrasound. The present safety study was therefore designed to explore effects of beneficial ultrasound characteristics on the infarcted and non-infarcted myocardium.

METHODS

In an open chest porcine model (n = 17), myocardial infarction was induced by ligating a coronary diagonal branch. Pulsed ultrasound of frequency 1 MHz and intensity 0.1 W/cm2 (ISATA) was applied during one hour to both infarcted and non-infarcted myocardial tissue. These ultrasound characteristics are similar to those used in studies of ultrasound enhanced thrombolysis. Using blinded assessment technique, myocardial damage was rated according to histopathological criteria.

RESULTS

Infarcted myocardium exhibited a significant increase in damage score compared to non-infarcted myocardium: 6.2 +/- 2.0 vs. 4.3 +/- 1.5 (mean +/- standard deviation), (p = 0.004). In the infarcted myocardium, ultrasound exposure yielded a further significant increase of damage scores: 8.1 +/- 1.7 vs. 6.2 +/- 2.0 (p = 0.027).

CONCLUSION

Our results suggest an instantaneous additive effect on the ischemic damage in myocardial tissue when exposed to ultrasound of stated characteristics. The ultimate damage degree remains to be clarified.