Cryptogenic Stroke In The Context of Pandemic-Related Stress: The Role of Arterial Hemodynamics.

BACKGROUND: Up to 45% of ischemic strokes are cryptogenic, which is an impediment to proposing preventative measures. In this investigation we aimed to study underlying heart arrhythmias in patients with cryptogenic stroke, taking into consideration the context of the COVID-19 pandemic and stressful lockdown conditions. SUBJECTS AND METHODS: In this cross-sectional study we observed 52 patients with cryptogenic stroke >1 month after acute presentation, and a control group consisting of 88 patients without stroke. All patients undewent the laboratory and instrumental investigation consisting of the following: lipid spectrum; hemostasiograms; hemoglobin A1c; transthoracic or/and transesophageal echocardiography; 24-hours monitoring of ECG; computer tomography or magnetic resonance imaging of the brain. We studied the hemodynamics of the common carotid arteries using Doppler ultrasound imaging and digital sphygmography (SG). RESULTS: The groups were indentical with respect to the preponderance of study parameters (sex, age, comorbidities, instrumental and laboratory data). The ischemic stroke group had a statistically significant difference in the prevalence of the first type of extrasystolic arrhythmia according to our gradation of extrasystoles, which are ventricular systoles of extrasystolic contraction appearing before the transmitral blood flow peak (peak E in echocardiography). We observed that earlier ventricular systoles of extrasystole in the cardiac cycle predicted for greater growth of hemodynamic and kinetic parameters. Calculating the indices of a four-field table established the significant relationship between the moment of appearance of extrasystolic ventricular contraction in the cardiac cycle and the risk for cryptogenic stroke (normalized value of the Pearson coefficient (C`) of the two paramaters was 0.318). CONCLUSIONS: Extrasystolic arrhythmia appeared as an additional risk factor of earlier stroke. The most dangerous type of arrhythmia was when the ventricular contraction of the extrasystole appeared before the transmitral blood flow peak in the cardiac cycle. This observation could present a risk-marker for brain-related cardiovascular complications such as stroke, which might be patients suffering from different internal diseases, especially in the context of environmental stress conditions of the current pandemic and its related lockdown measures.

Electrophysiological relation between the superior vena cava and right superior pulmonary vein in patients with paroxysmal atrial fibrillation.

INTRODUCTION: The superior vena cava (SVC) is a main source of nonpulmonary vein (PV) ectopies initiating atrial fibrillation (AF). Empiric SVC isolation may improve rhythm outcomes after catheter ablation of AF. Because the SVC passes immediately adjacent to the right superior PV (RSPV), an electrophysiological relation could be present between the two structures. The present study aimed to estimate the interrelation between the SVC and RSPV by evaluating arrhythmogenic activities observed during catheter ablation of AF. METHODS AND RESULTS: Study subjects comprised 121 consecutive patients referred for catheter ablation of paroxysmal AF. Isoproterenol infusion was used to induce ectopies and AF. Patients were divided into two groups depending on the presence of arrhythmogenic SVC: arrhythmogenic-SVC (A-SVC) and nonarrhythmogenic SVC (Non-A-SVC) groups. The prevalence of females was higher and body surface area was smaller in the A-SVC group (N = 22) than Non-A-SVC group (N = 99). Arrhythmogenic activities were observed in 60 (49%) RSPVs, 24 (20%) right inferior PVs, 72 (59%) left superior PVs, and 31 (25%) left inferior PVs. Arrhythmogenic RSPVs were more prevalent in the A-SVC group than Non-A-SVC group (86% vs. 41%, P = 0.0001), whereas these prevalences in the other three PVs were not different between groups (P >0.3). In multivariable analysis, arrhythmogenic RSPV was the only independent predictor of arrhythmogenicity of the SVC (OR, 8.53; 95% CI 2.31-31.46; P = 0.001). CONCLUSIONS: An electrophysiological interrelation may be present between the SVC and RSPV in patients with paroxysmal AF. Semiempiric SVC isolation limited to patients with an arrhythmogenic RSPV may be a more efficient treatment strategy.

Protective effects of estrogen against reperfusion arrhythmias following severe myocardial ischemia in rats.

BACKGROUND: Female sex hormones may have protective effects against arrhythmias, including reperfusion arrhythmias (RAs), but the mechanisms are still not completely known. METHODS AND RESULTS: Serial changes in rat hearts (rhythm, apoptosis and the its infuencing factors; cardiac vinculin mRNA expression and connexin43 (Cx43) dephosphorylation) were examined during periods of ischemia-reperfusion with and without estrogen treatment. After reperfusion, although the incidence of arrhythmias became higher in both the vehicle-group and estrogen-group, compared with the ischemia period, estrogen prevented reperfusion-induced upregulation of the incidence of arrhythmias, especially ventricular premature beats (VPB) and ventricular tachycardia (VT). The duration of VT and fibrillation, and the number of VPB and VT, were all significantly decreased in the estrogen-group. The expression of cardiac vinculin mRNA decreased significantly in the vehicle-group but not in the estrogen-group. Cx43 dephosphorylation and myocyte apoptosis increased in both groups, but the values for the estrogen-group were all markedly lower than those for the vehicle-group. A selective estrogen receptor (ER) beta agonist prevented reperfusion-induced upregulation of the incidence of both VPB and VT significantly; a selective ERalpha agonist had no significant influence. CONCLUSIONS: Estrogen can protect the heart against RAs, at least in part, mediated through gap junctions. Upregulation of ERbeta but not ERalpha mediated most of the estrogen-induced cardioprotection against RA.

Ectopy in trauma patients: cautions for use of heart period variability in medical monitoring.

INTRODUCTION: Heart period variability measurements have been proposed for use in early prediction of mortality or the requirement for lifesaving interventions in trauma patients. However, the presence of even one ectopic beat (EB) and/or electromechanical noise compromises the accurate calculation of heart period variability. We tested the hypothesis that ECGs from trauma patients exhibit a greater frequency of EBs than healthy human research subjects. METHODS: Continuous ECGs were recorded in 20 healthy human subjects at rest, 108 healthy human subjects undergoing experimentally induced progressive central hypovolemia (via lower body negative pressure, LBNP), and 245 trauma patients. The proportions of subjects/patients with at least one EB were identified in each group. RESULTS: ECG waveforms from 20% and 18% of healthy human subjects at rest or undergoing LBNP, respectively, contained at least one EB. ECG waveforms from 36% of the trauma patients were found to contain either EBs (35%) or electromechanical noise (1%). CONCLUSIONS: A significant number of EBs occur in healthy subjects both at rest and during progressive reduction in central blood volume, and trauma is associated with a near doubling of this incidence. As both EBs ' and noise result in invalid heart period variability calculations, these metrics as currently calculated could not be used in approximately 36% of trauma patients. The limited use in nearly two of every five trauma patients indicate that it is unlikely that continuous heart period variability measurements could substantially improve pre-hospital or emergency room decision-support in trauma.

Influence of irregular heart rhythm on radiation exposure, image quality and diagnostic impact of cardiac computed tomography angiography in 4,339 patients. Data from the German Cardiac Computed Tomography Registry.

BACKGROUND: Coronary computed tomography angiography (coronary CTA) provides non-invasive evaluation of the coronary arteries with high precision for the detection of significant coronary artery disease (CAD). AIM: To investigate whether irregular heart rhythm including atrial fibrillation and premature beats during data acquisition influences (i) radiation and contrast media exposure, (ii) number of non-evaluable coronary segments and (iii) diagnostic impact of coronary CTA. METHODS: Twelve tertiary care centers with ≥64 slice CT scanners and ≥5 years of experience with cardiovascular imaging participated in this registry. Between 2009 and 2014, 4339 examinations were analysed in patients who underwent clinically indicated coronary CTA for suspected CAD. Clinical and epidemiologic data were gathered from all patients. In addition, clinical presentation, heart rate and rhythm during the scan, Agatston score, radiation and contrast media exposure and the diagnostic impact of coronary CTA were systematically analysed. RESULTS: Of 4339 patients in total, 260 (6.0%) had irregular heart rhythm, whereas the remaining 4079 (94.0%) had stable sinus rhythm. Patients with irregular heart rhythm were older (63.2 ± 12.5yrs versus 58.6 ± 11.4yrs. p < 0.001), exhibited a higher rate of pathologic stress tests before CTA (37.1% versus 26.1%, p < 0.01) and higher heart rates during CTA compared to those with sinus rhythm (62.5 ± 11.6bpm versus 58.9 ± 8.5bpm, p < 0.001). Both contrast media exposure and radiation exposure were significantly higher in patients with irregular heart rhythm (90 mL (95%CI = 80-110 mL) versus 80 mL (95%CI = 70-90 mL) and 6.2 mSv (95%CI = 2.5-11.7) versus 3.3 mSv (95%CI = 1.7-6.9), p < 0.001 for both). Coronary CTA excluded significant CAD less frequently in patients with irregular heart rhythm (32.9% versus 44.8%, p < 0.001). This was attributed to the higher rate of examinations with at least one non-diagnostic coronary segment in patients with irregular heart rhythm (10.8% versus 4.6%, p < 0.001). Subsequent invasive angiography could be avoided in 47.2% of patients with irregular heart rhythm compared to 52.9% of patients with sinus rhythm (p = NS), whereas downstream stress testing was recommended in 3.2% of patients with irregular heart rhythm versus 4.0% of patients with sinus rhythm (p = NS). CONCLUSION: A significant number of patients scheduled for coronary CTA have irregular heart rhythm in a real-world clinical setting. In such patients, heart rate during coronary CTA is higher, possibly resulting in (i) higher radiation and contrast agent exposure and (ii) more frequent coronary CTA examinations with at least one non-diagnostic coronary artery segment. However, this does not seem to lead to increased downstream stress testing or subsequent invasive procedures.

[Peculiar physiological reactions to +Gx loads of nonprofessional members of short-term missions to the ISS].

Physiological reactions to +Gx loads of 10 nonprofessional members of 8 to 12-d. missions to the ISS some of whom had partial health defciency were compared with data about space station MIR cosmonauts (n=10) who participated in flights of similar duration but were qualified as essentially healthy. Age of the ISS visitors varied between 29 and 60 years, whereas the MIR cosmonauts were 31 to 49 years old. Based on analysis of objective information, the ISS visitors were distinguished by much more pronounced sinus tachycardia and tachypnea during insertion and re-entry. There were several instances of pre-launch extrasystole arrhythmias that persisted during insertion and were, as a rule, more serious during re-entry. Also, descent from orbit caused more frequent cardiac rhythm disturbances, polymorphism and severity in these space flyers in comparison with the MIR cosmonauts. Particularly grave ECG deviations were observed in two 60-y.o. crew members. However, all these disturbances were episodic by character. These results suggest that development of individual programs of medical risk mitigation for nonprofessional flyers to the ISS should give regard for the status of cardiac rhythm regulation as re-entry g-loads may affect ECG dramatically. Besides, the analysis highlighted the necessity of more rigorous selection of aged candidates for ISS missions with partial health deficiency

Avoiding interpretive pitfalls when assessing arrhythmia suppression after myocardial infarction: insights from the long-term observations of the placebo-treated patients in the Cardiac Arrhythmia Pilot Study (CAPS)

The Cardiac Arrhythmia Pilot Study (CAPS) was a 1 year trial that analyzed the safety and effectiveness of arrhythmia suppression in 502 patients surviving acute myocardial infarction who had greater than or equal to 10 ventricular premature depolarizations/h or greater than or equal to 5 runs of ventricular tachycardia on a Holter recording obtained 6 to 60 days after the acute infarction. Because 100 of these patients received placebo in a double-blind fashion for 1 year, a comprehensive objective analysis was performed of spontaneous arrhythmia changes based on real data rather than statistical estimates. In the CAPS placebo group, 19% developed some serious clinical event in 1 year (death, heart failure, proarrhythmia) that could likely be attributable to antiarrhythmic drug toxicity. A significant reduction in the frequency of ventricular premature depolarizations (p = 0.004) occurred in the first few weeks of "therapy" with a further significant (p less than 0.04) decrease between 3 to 12 months. After initiation of placebo antiarrhythmic therapy, 27% had "apparent ventricular premature depolarization suppression" (greater than or equal to 70% reduction) after one Holter recording evaluation and nearly half (48%) after six Holter recordings to assess suppression were performed.(ABSTRACT TRUNCATED AT 250 WORDS)

Effects of carbon monoxide exposure in patients with documented cardiac arrhythmias.

OBJECTIVE: This study was designed to determine whether carbon monoxide has proarrhythmic effects at rest and during upright exercise in patients with myocardial ischemia and moderate baseline ectopic activity. BACKGROUND: Exposure of patients with documented myocardial ischemia to low levels of carboxyhemoglobin (COHb) alters the myocardial response to exercise. Anecdotal reports from patients with myocardial ischemia have noted the development of arrhythmias related to carbon monoxide exposure. Increased frequency of arrhythmias related to carbon monoxide exposure in patients performing supine bicycle exercise has been recently reported. METHODS: Twenty-eight nonsmoking men and five nonsmoking women with documented coronary artery disease and a minimum of 30 ventricular ectopic beats/h over a 20-h period were studied. Subjects were exposed in a randomized double-blind fashion to either room air or sufficient carbon monoxide to elevate their COHb concentration to 3% or 5% in 1 h, followed by a maintenance exposure to carbon monoxide. The subjects then left the laboratory and resumed their normal daily activity to determine changes in ventricular ectopic beats after carbon monoxide exposure. RESULTS: There was no significant change in the frequency of single ventricular ectopic beats at rest from 115 +/- 28 (in room air) to 121 +/- 31 at 3% COHb to 94 +/- 23 at 5% COHb. Exercise itself increased the frequency of ventricular ectopic beats, but there was no additional effect of carbon monoxide exposure on the exercise-induced increase in isolated ectopic beats or complex ectopic waveforms. Analysis of the data based on grouping of the subjects by the severity of disease (ventricular ectopic beat frequency, ejection fraction, presence of exercise-induced ischemia) indicated no proarrhythmic effect of carbon monoxide. CONCLUSIONS: In patients with frequent ventricular ectopic activity (> or = 30 ectopic beats/h), exposure to carbon monoxide producing either 3% or 5% COHb does not increase arrhythmia frequency of single or multiple beats during rest or exercise.

Prevalence of the coexistence of left ventricular false tendons and premature ventricular complexes in apparently healthy subjects: a prospective study in the general population.

The prevalence of left ventricular false tendons, premature ventricular complexes and their coexistence was evaluated prospectively in 187 healthy company workers aged 21 to 50 (mean 36) years. False tendons were demonstrated echocardiographically in 133 (71%). Eight subjects were withdrawn from the study because of silent mitral valve prolapse. In these 179 healthy subjects, false tendons were detected in 127 (71%) and premature ventricular complexes in 48 (27%). Their coexistence was observed in 40, which showed a significant correlation (p less than 0.05) of false tendons and premature ventricular complexes. In seven of the eight subjects without false tendons, premature ventricular complexes were uniform and infrequent (mean 3 beats/24 h). In the 40 subjects with false tendons, premature ventricular complexes were uniform in 29, multiform in 6 and repetitive in 5, and the mean frequency was 96 beats/24 h. Correlation of premature ventricular complexes with the type of false tendons showed that premature ventricular complexes were significantly associated with thick (greater than or equal to 2 mm) and longitudinal tendons (p less than 0.005). Although it is not certain that left ventricular false tendons are arrhythmogenic, the prevalence of the coexistence of left ventricular false tendons and premature ventricular complexes in the general population, and the special relation between the frequency and the form of premature ventricular complexes and the type of false tendons, suggests that false tendons may play an etiologic role in the genesis of premature ventricular complexes in apparently healthy subjects.

Frequency of predischarge ventricular arrhythmias in postmyocardial infarction patients depends on residual left ventricular pump performance and is independent of the occurrence of acute reperfusion. The GISSI-2 Investigators.

OBJECTIVES: To test whether acute reperfusion of the infarct-related vessel after an acute myocardial infarction is associated with a subsequent reduction in spontaneous ventricular arrhythmias that is independent of ventricular ejection fraction, 1,944 patients from the GISSI-2 study population were studied. The patients were selected on the basis of a first myocardial infarction and the availability of two-dimensional echocardiographic ejection fraction and data on the number of premature ventricular contractions per hour on Holter monitoring. BACKGROUND: It has been suggested that postthrombolytic reperfusion of the culprit vessel may be associated with an increased electrical stability of the infarcted heart, irrespective of its residual pump performance. METHODS: The predischarge relation between ejection fraction and number of premature ventricular contractions per hour was plotted according to the occurrence (1,309 patients) or not (635 patients) of acute reperfusion, identified noninvasively according to the modifications of the ST segment in serial electrocardiograms obtained in the first 24 h after infarction. RESULTS: The frequency of premature ventricular contractions increased in a linear fashion with decreasing ejection fraction in both cohorts (p < 0.005 and p < 0.0001); however, there was no significant difference between the slopes and the intercepts of the two regression lines, so that the relation between ejection fraction and number of premature ventricular contractions per hour could be adequately described by a single equation: y (number of premature ventricular contractions) = 33.0-0.42x (ejection fraction) (r = -0.107, p < 0.0001). The results were the same even when differences between group characteristics were accounted for in a multiple regression model. CONCLUSIONS: It is concluded that 1) the number of premature ventricular contractions per hour after an acute myocardial infarction is dependent in a linear, inverse fashion on the residual ventricular ejection fraction, and 2) this relation is independent of the occurrence of reperfusion in the acute phase of infarction.

Ventricular ectopic activity: prevalence and risk.

Ambulatory electrocardiographic monitoring and the frequent use of stress electrocardiography have been important tools in characterizing the prevalence and prognostic importance of ventricular ectopic activity in both healthy persons and patients with organic heart disease. These studies have demonstrated that ventricular ectopy is not uncommon in persons with no evidence of heart disease. However, it is rarely of high density or repetitive, and even when frequent or repetitive, or both, carries little, if any, risk of sudden death in patients without syncope. However, in patients with organic heart disease and in certain clinical settings, frequent and repetitive ventricular ectopy identifies a population at high risk for arrhythmia-induced syncope or sudden death. These rhythm disturbances have particular prognostic importance in ischemic heart disease with depressed left ventricular function and hypertrophic cardiomyopathy. Patients with presyncope or syncope and structural heart disease who demonstrate frequent and repetitive ventricular ectopy are also a high-risk group. Therefore, individual risk stratification is important in deciding whether and how to treat patients with ventricular ectopy.

Diuretics, serum potassium and ventricular arrhythmias in the Multiple Risk Factor Intervention Trial.

To examine the relation between diuretic use and ventricular premature complexes (VPCs) in the Multiple Risk Factor Intervention Trial, data derived from the baseline and annual rest electrocardiograms were analyzed for men in the special-intervention (SI) and usual-care (UC) groups. At baseline, age, diuretic use and presence of other rest electrocardiographic abnormalities were significantly associated with the prevalence of VPCs. Among diuretic users at baseline, those with lower serum potassium levels were most likely to have VPCs. Over the follow-up period among nonhypertensive persons the relative risk (SI/UC) for the occurrence of VPCs during follow-up was 0.83, and for hypertensives this relative risk increased linearly from 1.08 to 1.42, with higher levels of diastolic blood pressure at entry (p less than 0.01 for linear trend of relative risk estimates). This was due to an increasing risk among the SI group, and the risk was independent of the presence or absence of rest electrocardiographic abnormalities at baseline. The relative risk estimate, diuretic vs no diuretic, for development of VPCs was approximately 1.2 (p = 0.04) for SI men and 1.1 (p = 0.35) for UC men. The reduction in serum potassium level was greater for those with VPCs, and regression analysis showed that low serum potassium levels were significantly associated with the incidence of VPCs in both study groups. These data confirm and quantify the relation between diuretic drugs and VPCs and suggest that at least 1 mechanism of diuretic-induced VPCs is potassium depletion.

Ventricular arrhythmias in postoperative tetralogy of Fallot.

Ventricular arrhythmias in patients after total surgical repair of tetralogy of Fallot have been associated with late sudden death. In this large multicenter retrospective study of 359 patients with postoperative tetralogy of Fallot, spontaneous ventricular premature complexes (VPCs) on 24-hour ambulatory electrocardiographic monitoring and laboratory-induced ventricular tachycardia (VT) by electrophysiologic stimulation were analyzed. The mean age at surgical repair was 5 years and the mean follow-up duration after repair was 7 years. Spontaneous VPCs on ambulatory monitoring were found in 48% and induced VT on electrophysiologic stimulation was found in 17% of patients. Both spontaneous VPCs and induced VT were significantly related to delayed age at repair, longer follow-up interval, symptoms of syncope or presyncope and right ventricular systolic hypertension (greater than 60 mm Hg) (p less than 0.05), but not to right ventricular diastolic pressure greater than 8 mm Hg. The VPCs on ambulatory monitoring were more complex with increasing age at repair and follow-up duration. Induction of VT on electrophysiologic stimulation correlated with spontaneous VPCs including VT on 24-hour ambulatory electrocardiographic monitoring. The electrophysiologic stimulation protocol varied and the induction of VT increased with a more aggressive stimulation protocol. While induced sustained monomorphic VT was related to all forms of spontaneous VPCs, induced nonsustained polymorphic VT was related to more complex forms of VPCs on ambulatory monitoring. VT was not induced in asymptomatic patients who had normal 24-hour ambulatory electrocardiographic monitoring and normal right ventricular systolic pressure. (ABSTRACT TRUNCATED AT 250 WORDS)

Prevalence, characteristics and significance of ventricular premature complexes and ventricular tachycardia detected by 24-hour continuous electrocardiographic recording in the Cardiac Arrhythmia Suppression Trial. CAST Investigators.

The prevalence, characteristics and significance of ventricular arrhythmias detected by ambulatory electrocardiography were evaluated in 1,498 patients who were randomized to encainide, flecainide or placebo in the Cardiac Arrhythmia Suppression Trial. The mean ventricular premature complex (VPC) frequency at baseline was 133 +/- 257 VPCs/hour. Nonsustained ventricular tachycardia (VT) (rate greater than or equal to 120 beats/min) was present in 22% of patients. Accelerated idioventricular rhythm (rate less than 120 beats/min) occurred in 22% of subjects. There were 63 deaths/resuscitated cardiac arrests in the active treatment (encainide/flecainide) group and 26 in the placebo group. In the treatment group mortality increased with increasing VPC frequency, (p = 0.006), whereas in the placebo group such a relation was not present. Mortality/resuscitated cardiac arrest increased in patients with greater than or equal to 2 VT episodes than in those with less than or equal to 1 episode in the active treatment group (p = 0.04). There was no significant association between VT and mortality/resuscitated cardiac arrest in the placebo group. The presence of accelerated idioventricular rhythm was not associated with increased mortality/resuscitated cardiac arrest in either the active treatment or placebo groups. However, mortality was lower in patients with accelerated idioventricular rhythm rates less than 100 beats/min than in those with rates greater than or equal to 100 beats/min (p = 0.05). Thus, in the Cardiac Arrhythmia Suppression Trial the previously described association between mortality/resuscitated cardiac arrest and ventricular arrhythmias (VPC and VT) were only observed in the active treatment group. In addition, based on the results obtained in this highly selected population, it is suggested that the definition of accelerated idioventricular rhythm should be a rate less than 100 beats/min, and at a rate greater than or equal to 100 beats/min it should be categorized as VT.

Long-term prognostic significance of ambulatory electrocardiographic findings in apparently healthy subjects greater than or equal to 60 years of age.

To determine the long-term prognostic significance of frequent or complex ectopic beats and ST-segment changes on 24-hour ambulatory electrocardiogram (ECG) in apparently healthy older subjects, 98 volunteers were followed up from the Baltimore Longitudinal Study of Aging who were 60 to 85 years old and free of cardiac disease by history, physical examination and maximal treadmill testing at the time of ambulatory ECG between 1978 and 1980. Over a mean follow-up period of 10 years, coronary events developed in 14 subjects: angina pectoris in 7, nonfatal myocardial infarction in 3 and sudden cardiac death in 4. The incidence of coronary events did not differ significantly between subjects who developed the following arrhythmias and those who did not, respectively: greater than or equal to 30 supraventricular ectopic beats in any hour, 18 vs 13%; greater than or equal to 100 supraventricular ectopic beats in 24 hours, 20 vs 12%; paroxysmal atrial tachycardia, 15 vs 14%; greater than or equal to 30 ventricular ectopic complexes (VECs) in any hour, 17 vs 14%; greater than or equal to 100 VECs in 24 hours, 18 vs 14%; or repetitive VECs, 20 vs 13%. The mean 24-hour heart rate (75 +/- 8 vs 72 +/- 9 beats/min) as well as the maximal (116 +/- 20 vs 111 +/- 18 beats/min) and minimal (51 +/- 6 vs 53 +/- 7 beats/min) heart rate also did not differ between the coronary event and non-event groups.(ABSTRACT TRUNCATED AT 250 WORDS)

Usefulness of Holter monitoring in predicting efficacy of amiodarone therapy for sustained ventricular tachycardia associated with coronary artery disease.

The ability of Holter monitoring to predict clinical events during amiodarone therapy was evaluated in 83 patients with coronary artery disease and inducible monomorphic ventricular tachycardia. Sixty-four patients (77%) had significant ventricular ectopy activity (> or = 10 ventricular premature complexes [VPCs]/hour) at baseline, and 19 (23%) did not; patients were similar in age (63 and 65 years, respectively; p = 0.24) and ejection fraction (31 and 32%, respectively; p = 0.75). Over a mean of 23 +/- 17 months, there was no difference in arrhythmia recurrence (33 and 26%; p = 0.89) or sudden death (16 and 20%; p = 0.94) in patients with and without significant ectopy, respectively. In patients with significant ectopy, amiodarone decreased VPC frequency from baseline to 2 weeks, but not from 2 to 6 weeks. Forty-two patients had > 85% reduction in ectopy at 2 weeks; 20 patients did not. However, this reduction of simple VPCs did not predict a decrease in arrhythmic recurrence (29 vs 40%; p = 0.59) nor sudden death (25 vs 11%; p = 0.56) in patients with and without VPC suppression, respectively. Forty-five patients had Holter monitoring at 6 weeks. Twenty-one patients (47%) had > 95% suppression of ectopy, and 24 did not. Neither the recurrence (38 vs 38%; p = 0.54) nor sudden death (33 vs 13%; p = 0.45) rate was predicted by the degree of VPC suppression. Amiodarone is a powerful suppressant of VPCs, but Holter suppression of this ectopic activity is not predictive of clinical outcome.

Variability of the ventricular response in atrial fibrillation and prognosis in chronic nonischemic mitral regurgitation.

Although reduced heart rate (HR) variability during sinus rhythm is associated with an adverse prognosis in a variety of clinical settings, the significance of measures of variability of the ventricular response in atrial fibrillation (AF) requires clarification. AF is common among patients with chronic severe mitral regurgitation (MR) and potentially limits the application of HR variability techniques in this population. Therefore, this study examined the physiologic correlates and prognostic significance of measures of HR variability in 21 patients with nonischemic causes of chronic severe MR who had chronic AF and underwent 24-hour ambulatory electrocardiography as part of a prospective study of the natural history of regurgitant valvular heart disease. Patients were followed for up to 9.1 years and end points of mortality and progression to mitral valve surgery were tabulated. Time- and frequency-domain measurements of high-, low-, and ultra-low-frequency HR variability were computed and compared with resting ventricular function by radionuclide cineangiography and outcome. All measures of HR variability were covariate (pair-wise r values between 0.48 and 0.99, all p values < 0.03), and none of the variables was significantly related to age, ventricular premature complex (VPC) density, or right or left ventricular ejection fraction. Reductions in time-domain measurements of ultra-low- and high-frequency HR variability were significant predictors of the combined risk of mortality or requirement for mitral valve surgery (p = 0.02 and p = 0.05, respectively).(ABSTRACT TRUNCATED AT 250 WORDS)

Late sudden cardiac death in the follow-up of patients having a heart valve prosthesis.

Eight hundred thirty-one patients with Björk-Shiley prostheses (341 aortic, 345 mitral, and 145 double) had a mean follow-up time of 68.2 months per patient. Of these, 24 (16% of all deaths) died suddenly: six of 42 with aortic valve replacement (14.3%), 12 of 56 with mitral valve replacement (21.4%), and six of 36 with double valve replacement (16.6%). This correlated with evidence of premature ventricular complexes detected in multiple routine 12-lead follow-up electrocardiograms (p less than 0.001 for simple aortic or mitral valve replacements and p less than 0.01 for combined aortic and mitral valve replacements). Premature ventricular complexes were significantly more frequent among those who died suddenly than among survivors and those who died of other causes (p less than 0.001 in both cases); there were no significant differences between the latter two groups. The actuarial risk of sudden death was significantly greater among those patients who had premature ventricular complexes than among those who did not have this disorder (p = 0.0002). We conclude that the presence of premature ventricular complexes, as an independent variable, was correlated with the risk of sudden death.

The prognostic significance of very low frequency ventricular ectopic activity in survivors of acute myocardial infarction. BHAT Study Group.

Survivors of myocardial infarction with less than 2 PVC/h on 24-h ambulatory electrocardiography were followed up for an average of 25 months (11 to 40 months) while receiving a placebo (1,222 patients) or propranolol, 180 or 240 mg/day (1,234 patients). Three quarters of the participants with PVCs had an average of less than 2 PVC/h. Only 16 percent did not have any ventricular ectopic activity during the 24 h. Analysis of total mortality according to the number of premature ventricular complexes per hour showed that patients who had PVCs with a very low frequency (less than 0.5/h) had 49 percent higher mortality than patients who did not have any PVC. Patients who had greater than 0.5 PVC/h but less than 1 PVC/h had a statistically significant higher mortality rate, 11.7 vs 4.1 percent (p less than 0.0001) than patients who had no PVC. These data indicate that low ventricular ectopic activity frequency is associated with increased mortality in survivors of acute myocardial infarction.

Eye hue and the oculocardiac reflex.

During operations for squint nodal rhythm and other more serious arrhythmias such as heart block and multifocal ventricular extrasystoles, as well as the oculocardiac reflex, are shown to occur more frequently in patients with brown or hazel eyes than in patients with blue or grey eyes.