Electrocardiographic markers of structural heart disease and predictors of death in 2332 unselected patients undergoing outpatient Holter recording.

AIMS: To test the hypothesis that the QS interval of ventricular ectopic beats (VEBs) (ventricular ectopic QS interval, VEQSI) would provide a marker for the presence of structural heart disease and a predictor of mortality. METHODS AND RESULTS: We interviewed and examined 2332 patients undergoing Holter ECG monitoring for clinical indications. In persons with VEBs, the morphologies were counted and the QS interval was measured for each of these morphologies. The duration of the broadest VEB, measured from the QRS onset in the derivation showing the earliest onset to its end in the derivation showing the latest termination, was taken as that patient's VEQSI. Survival was ascertained from public health records. Of 15 electrocardiographic variables pre-selected as potential prognostic indicators, VEQSI demonstrated the strongest association with the presence of structural heart disease (P = 0.013). Thirty-four persons died in 16 +/- 4 months follow-up. Univariate predictors of mortality are age, history of myocardial infarction, maximum heart rate, QS interval, the number of VEB morphologies, and the VEQSI. On multivariate analysis, only age (P < 0.001) and the number of VEB morphologies (P = 0.02) predicted mortality. CONCLUSION: VEQSI predicts the presence of structural heart disease. The number of VEB morphologies in a Holter recording predicts all-cause mortality.

Distribution and prognostic significance of QT intervals in the lowest half centile in 12,012 apparently healthy persons.

The presence of an abnormally short QT interval has been noted among survivors of idiopathic ventricular fibrillation and among close relatives of victims of unexplained sudden death. Most reported cases have had rate-corrected QT (QTc) intervals of <300 ms. The prevalence of such values in the community has not been documented. We reviewed the electrocardiograms (ECGs) of 12,012 subjects who underwent routine medical examinations for occupational reasons. The QT interval was measured by 2 physicians in all cases, and QTc interval was calculated. All ECGs with QTc values in the lowest 5% were reviewed by 2 cardiologists expert in QT analysis, and the QT measurement was corrected if necessary. Information about subsequent survival was obtained from the case file or from public records. In the lowest 1/2 centile, the distribution of QTc values continued to follow a normal pattern without evidence of a distinct subpopulation of low values. The shortest QTc encountered was 335 ms. Information about subsequent survival was available for 36 of the 60 subjects with the lowest 1/2 centile of QTc values. None of these subjects died during the 7.9 +/- 4.5 years subsequent to the ECG that demonstrated the short QT interval. In conclusion, a QTc interval of

Fractal correlation properties of R-R interval dynamics in asymptomatic relatives of patients with dilated cardiomyopathy.

BACKGROUND AND AIM: asymptomatic relatives of patients with familial dilated cardiomyopathy who have left ventricular enlargement [LVE] are at risk for progression to dilated cardiomyopathy. A novel index of the fractal correlation properties of heart rate variability (HRV), the short-term scaling component (proportional, variant(1)) in detrended fluctuation analysis, is a promising prognostic tool in left ventricular dysfunction. The aim of this study was to compare values of proportional, variant(1) and conventional HRV indices in LVE relatives with dilated cardiomyopathy patients and normal controls. METHODS: time-domain and spectral HRV measures, and the short-term scaling component ( proportional, variant(1)) were assessed from 24-h Holter recordings from 22 LVE relatives (left ventricular end-diastolic dimension >112% predicted, normal fractional shortening), 24 dilated cardiomyopathy patients and 14 controls. RESULTS: the time domain index SDNN was lower in dilated cardiomyopathy patients [101.8(+/-44.0)] than in LVE relatives [161.7(+/-53.9)] or controls [152.9(+/-51.4)], P=0.01. Similarly, triangular index and spectral measures were reduced in dilated cardiomyopathy patients but not in LVE relatives or controls. In contrast, the short term scaling component ( proportional, variant(1)) in detrended fluctuation analysis was reduced in both dilated cardiomyopathy patients [1.06(+/-0.33)] and in LVE relatives [1.15 (+/-0.20)], compared with controls [1.32(+/-0.16)], P=0.01. Among DCM patients the short-term scaling component ( proportional, variant(1)) was significantly associated with echocardiographic deterioration during follow-up (3.7+/-2.1 year) (P=0.004). CONCLUSION: the short-term scaling component ( proportional, variant(1)) is reduced in asymptomatic relatives of dilated cardiomyopathy patients who have LVE.

Arrhythmic complications of electrical cardioversion: relationship to shock energy.

BACKGROUND: Existing guidelines for electrical cardioversion (ECV) of atrial arrhythmias suggest starting at a low energy setting on the grounds that shocks of high energy might damage the myocardium or trigger more serious arrhythmias. We hypothesised that more powerful shocks would exceed the upper limit of vulnerability for inducing ventricular fibrillation. The initial use of higher energy could therefore reduce arrhythmic complications. METHODS: We collected data on the sequence of shocks delivered and the resulting changes in cardiac rhythm in 1896 patients who underwent transthoracic ECV. Rhythm strips derived from 200 consecutive ECV attempts were studied to verify the accuracy of the synchronisation of the shocks delivered. RESULTS: In 2522 attempts at transthoracic ECV, 6398 shocks were delivered, 1243 in atrial flutter or atrial tachycardia, the others in AF. Ventricular fibrillation was significantly more common after shocks of < 200 J (5 of 2959 vs. 0 of 3439 shocks, p<0.05, Fischer's exact test). Conversion of atrial flutter or atrial tachycardia to AF was also more common at < 200 J (20 of 930 shocks vs. 1 of 313 shocks at > or = 200 J, p<0.05, chi2 test). Sinus bradycardia or sinus arrest complicated 0.95% of cardioversion attempts, but none required emergency pacing. The incidence of bradycardia was not related to the energy used. CONCLUSIONS: Shocks of > 200 J are associated with fewer tachyarrhythmic complications, and do not increase the risk of other serious complications. Bradycardia after cardioversion is very rarely of clinical importance.

Appropriateness of ECG Holter requests in an outpatient service: a prospective study.

BACKGROUND: Electrocardiographic ambulatory ECG monitoring plays a central role in the diagnostic evaluation of patients with cardiac arrhythmias. We sought to evaluate the appropriateness of the prescription of ECG Holter recordings performed at our centre. METHODS: We interviewed 2489 consecutive patients (49% male, aged 61 +/- 32 years) undergoing ECG Holter. We recorded the indication for the examination, the clinical characteristics of the patient and the speciality of the prescribing physician. The appropriateness of the test was evaluated. RESULTS: We evaluated 2489 consecutive Holter recordings, of which 1298 (52%) were found to have been clearly appropriate (class I), 311 (13%) as probably or possibly appropriate (class II), and 880 (35%) as inappropriate (class III). The test was requested by a cardiologist in 776 cases (31%), of which 56.2% had a class I indication, 13.4% class II, and 30.4% class III. Tests requested by a non-cardiologist were clearly appropriate (class I) in 50% of cases, whereas 12% had a class II indication, and 38% were in class III. Supraventricular tachycardia was present in 33.4% of recordings with a class I indication, 9% of those in class II, and 57.6% of those in class III. Non-sustained ventricular tachycardia was present in 6% of those with class I indications, 2.6% of those in class II, and 7.4% of those in class III. CONCLUSION: Our data showed that the majority of Holter recordings prescribed in our region are appropriate. Tests prescribed by cardiologists constitute only 31% of the total volume, but are more often appropriately prescribed.

Feasibility and safety of a simplified draping method for pacing procedures.

AIMS: Traditional draping for pacing procedures is time-consuming. We evaluated prospectively the safety of a simplified method using a single adhesive drape intended for use in cardiac catheterization. METHODS AND RESULTS: A single disposable adhesive drape was used in each of 250 consecutive pacing procedures by the same operator including 200 device implants and 50 revision procedures. We compared the results with those of 114 procedures performed in the same cardiac catheterization laboratory by three other operators using traditional draping methods for most cases. In the study group, no wound or pacemaker pocket infection, device erosion, or endocarditis was observed within the first 6 months after the procedure (0%, 95% CI 0-1.2%). One suspected infection occurred at 10 months (0.4%, 95% CI 0.1-2.2%). In the control group, there were two cases of early infection or suspected infection (2 of 114 procedures, 1.8%, 95% CI 0.27-6.1%), four cases of confirmed or suspected infection more than 6 months after the procedure giving an overall infection rate (6 of 114, 5.3%, 95% CI 2.1-11.0%) significantly higher than in the study group (P = 0.014, Fisher's exact test). CONCLUSION: A simplified draping method involving a single adhesive fenestrated drape can be used for pacemaker or ICD implantation or revision procedures without an excessively elevated risk of infective complications.