To allow an exchange of measurements and criteria between different electrocardiographic (ECG) computer programs, an international cooperative project has been initiated aimed at standardization of computer-derived ECG measurements. To this end an ECG reference library of 250 ECGs with selected abnormalities was established and a comprehensive reviewing scheme was devised for the visual determination of the onsets and offsets of P, QRS, and T waves. This task was performed by a group of cardiologists on highly amplified, selected complexes from the library of ECGs. With use of a modified Delphi approach, individual outlying point estimates were eliminated in four successive rounds. In this way final referee estimates were obtained that proved to be highly reproducible and precise. This reference data base was used to study measurement results obtained with nine vectorcardiographic and 10 standard 12-lead ECG analysis programs. The medians of program determinations of P, QRS, and T wave onsets and offsets were close to the final referee estimates. However, an important variability could be demonstrated between measurements from individual programs and mean differences from the referee estimates amounted to 10 msec for QRS for certain programs. In addition, the variances of all programs with respect to the referee point estimates were variable. Some programs proved to be more accurate and stable when the data from high-vs low-noise recordings were analyzed. Average Q wave durations calculated from ECGs for which programs agreed on the presence of a Q or QS wave differed by more than 8 msec in several program-to-program comparisons. Such differences may have important consequences with respect to diagnostic performance. Various factors that might explain these differences have been determined. The present study demonstrates that to allow an exchange of results and diagnostic criteria between different ECG computer programs, definitions, minimum wave requirements, and measurement procedures urgently need to be standardized.Circulation 71, No. 3, 523-534, 1985. DURING the last decade rapid growth has occurred in computer electrocardiographic (ECG) processing.1-3 At present, however, no standards for quantitative ECG analysis exist. There is a lack of agreement on The authors academic affiliations are listed in the Common Standards for Quantitative Electrocardiography (CSE) organizational structure that appears before the references.

In an effort to standardize terminology and criteria for clinical electrocardiography, and as a follow-up of its work on definitions of terms related to cardiac rhythm, an Ad Hoc Working Group established by the World Health Organization and the International Society and Federation of Cardiology reviewed criteria for the diagnosis of conduction disturbances and pre-excitation. Recommendations resulting from these discussions are summarized for the diagnosis of complete and incomplete right and left bundle branch block, left anterior and left posterior fascicular block, nonspecific intraventricular block, Wolff-Parkinson-White syndrome and related pre-excitation patterns. Criteria for intraatrial conduction disturbances are also briefly reviewed. The criteria are described in clinical terms. A concise description of the criteria using formal Boolean logic is given in the Appendix. For the incorporation into computer electrocardiographic analysis programs, the limits of some interval measurements may need to be adjusted.

In an effort to standardize and evaluate the performance of electrocardiographic computer measurement programs, a 15 lead reference library has been developed based on simultaneously recorded standard 12 lead and orthogonal XYZ lead data. A set of 250 electrocardiograms (ECGs) with selected abnormalities was analyzed by a group of five referee cardiologists and 11 different 12 lead and 6 XYZ computer programs. Attention was focused on the exact determination of the onsets and offsets of P, QRS and T waves. The referees performed their task on highly amplified, selected complexes from the library in a two round process. Median results of the referees coincided best with the median derived from all programs. An analysis of stability proved that the combined program median was a robust reference. However, some individual program results were widely divergent. Paired t tests demonstrated earlier onset for P and QRS (p less than 0.001), as well as later offset for P and T waves in the median 12 lead than in the XYZ results. Significant differences also existed among results obtained by programs analyzing all standard ECG leads at one time, the so-called multilead programs, and those obtained by the conventional standard three lead analysis programs. As a consequence, the derived P, PR, QRS and QT interval measurements varied quite widely among the various programs. Significant differences were also observed among measurements of Q, R and S duration. Some programs showed Q waves that were on the average 6 ms (p less than 0.001) longer than those of others. This may significantly influence diagnostic performance.(ABSTRACT TRUNCATED AT 250 WORDS)

An increasing body of evidence suggests that the potential for thrombotic complications is greater with nonionic than with ionic contrast agents. This is a particularly important consideration in the highly thrombogenic setting of percutaneous transluminal coronary angioplasty (PTCA). To explore this issue further, 500 consecutive patients undergoing PTCA were prospectively randomized to receive the low osmolality ionic ioxaglate or the nonionic agent iohexol. The number of acute thrombotic in-laboratory events was significantly less in the ioxaglate than in the iohexol group (8 versus 18; P < 0.05), but there was no significant difference between the 2 groups as regards the number of out-of-laboratory acute rethrombotic events. With multivariate analysis, use of the nonionic agent rather than the ionic agent emerged as an independent predictor of acute in-laboratory rethrombosis. These data suggest that, in the performance of PTCA, an ionic, rather than a nonionic, should be the preferred contrast agent.