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QT dispersion and mortality after myocardial infarction
872
Editor’s Comment: This is a retrospective review, but raises concerns for the evaluation of patients who are potentially preeclamptic.
0 SMOKING STATUS AS THE NEW VITAL SIGN: EFFECT ON ASSESSMENT AND INTERVENTION IN PATIENTS WHO SMOKE. Fiore MC, Jorenby DE, Schensky AE, et al. Mayo Clin Proc. 1995;70:209-13. The Centers for Disease Control have reported that fewer than 60% of smokers in the United States have ever been advised by their physician to quit smoking. Educational strategies such as lectures, conferences, and guidelines have minimally influenced physician behavior in this regard. In this prospective study, the authors surveyed patients before (N = 870) and after (N = 994) the implementation of smoking as a vital sign in an outpatient clinic setting. The survey asked whether patients were asked by the physician about their smoking status and whether they were urged to quit. A rubber stamp that included smoking status (current, former, never), as well as the traditional, was used at the beginning of the chart for each patient encounter. Medical assistants completed the vital sign portion of the chart. Patients reported being asked more often about smoking (58 vs. SlVo), being told to quit (49 vs. 70%), and being given specific advice on how to quit (24 vs. 43%) after the institution of smoking as a vital sign. All three of these criteria were statistically significant. The authors conclude that this low-cost intervention may be effective in reminding physicians to counsel their patients regarding tobacco use. An accompanying editorial notes [Christopher F. Richards, MD] that it is about time. Editor’s Comment: However, it is unlikely that the emergency department will be an appropriate environment for such interventions.
0 DO DOCTORS ACCURATELY ASSESS CORONARY RISK IN THEIR PATIENTS? PRELIMINARY RESULTS OF THE CORONARY HEALTH ASSESSMENT STUDY. Grover SA, Lowensteyn I, Esrey KL, et al. BMJ. 1995;310:975-8. This article details the results of a questionnaire survey performed in Ontario, Canada to evaluate the ability of doctors in primary care to assessa patient’s risk of coronary heart disease. Doctors from 24 selectedareas in urban and rural communities throughout Ontario, Canada were recruited for this study. During a 10 to 15 min break following a lecture on coronary health assessment,the participants were given a questionnaire which included a list of 14 coronary risk factors and two hypothetical cases. The doctors were asked to rate the importance of each coronary risk factor and to estimate the relative and absolute coronary risk of the two hypothetical patients (an “average” 30-year-old Canadian man and a IO-year-old Canadian woman). The results of the survey were compared to the
The Journal of Emergency Medicine
predictions made by the Coronary Heart Disease Prevention Model based on the Framingham Heart Study, the Canadian health survey, and Canadian life tables. Four hundred and forty-five doctors attended the meetings. Two hundred and fifty-three (57%) participated in the study and completed the questionnaire. One hundred and fortytwo doctors rated their confidence level as 3 or higher (1 being very confident and 10 not at all confident). For the 30-year-olds, doctors rated smoking as the most important risk factor and raised serum triglyceride concentrations as the least important risk factor. For the 70-year-olds, they rated diabetes as the most important risk factor and raised serum triglyceride concentrations as the least important. They rated each individual risk factor as significantly less important for the 70-year-olds than the 30-year-olds. The doctors overestimated the eight-year coronary risk for both hypothetical patients compared to the predictions made by the Coronary Heart Disease Model. Although the doctors overestimated the coronary risk, they were accurate in estimating the relative risk of the hypothetical patients compared with the age-matched and sex-matched Canadian averages. The doctors also overestimated the long-term benefits of modifying one or more specific risk factors. The authors found that experienced doctors’ assessments of the absolute risk of coronary diseasewere wrong but the assessmentsof the relative risk were correct. The authors concluded that with some recalibration and training, doctors might be able to predict accurately both relative and absolute risks. [Richard Chen, MD] Editor’s Comment: Accurately assessingcoronary risk factors may increase our diagnostic accuracy based on historical features.
0 QT DISPERSION AND MORTALITY AFTER MYOCARDIAL INFARCTION. Glancy JM, Garratt CJ, Woods KL, et al. Lancet. 1995;345:945-8. Approximately 3% of patients who suffer an acute myocardial infarction and are discharged from the hospital die of a dysrhythmic event within one year. With the advent of successful anti-dysrhythmic agents, attempts are being made to identify post-myocardial infarction patients at risk for sudden death. The authors of this retrospective study investigated the relationship of variance of QT intervals on electrocardiogram and subsequent death in patients admitted for myocardial infarction. One hundred and sixty-three patients who died between 24 hours and 61 months after myocardial infarction were compared with an age- and sex-matched group of patients who survived this period of time. The electrocardiographic (EKG) QT interval variance or dispersion was analyzed in these patients on days 2 or 3 post-infarct (the time of greatest dispersion), and at least 4 weeks later. Only 53 patients in the expired group and 82 patients in the living group had follow-up EKGs available. The QT dispersion was calculated as the difference between the longest and shortest QT intervals on an individual’s EKG. QT dispersion was then corrected for heart rate.
Abstracts
There was no significant difference in QT dispersion on early post-infarct EKGs between patients who survived and those who expired. However, the mean change in QT dispersion between early and follow-up EKGs was significantly greater in the group of patients who survived compared with those who expired. In addition to this notable difference, there were also differences in the rates of heart failure, previous infarctions, presence of bundle branch block, use of thrombolytic agents, and proportion of patients with inferior myocardial infarctions, between the patients who survived and those who died. The authors suggest that late QT dispersion may identify a subgroup of patients at higher risk of sudden death. [Christina Johnson, MD] Editor’s Comment: While the QT dispersion results are intriguing, there are a significant number of confounding variables that limit one’s ability to apply QT dispersion data in patient management at this time.
U CAN PATIENTS WITH NEUROMEDIATED ,SYNCOPE SAFELY DRIVE MOTOR VEHICLES? Sheldon R, Koshman ML. Am J Cardiol. 1995;75:955-6. Recent studies with head-up tilt table testing have shown that up to 75% of syncope is neuromediated. The authors of this study attempted to determine the risk of syncope while driving in those who have had a syncopal episode and a positive tilt table test. Two hundred and nine patients with a history of syncope who also had a positive tilt test were included in the analysis. Five patients had a history of fainting while driving a motor vehicle. Two of the.accidents resulted in injury to the driver, there were no fatalities, or pedestrian or passenger injuries. Considering these data, the authors estimate the risk per year of a syncopal episode with a resulting auto accident at 4/1,534 or 0.26%. The risk of harm was 2/l ,534 or 0.13%. The Canadian Cardio-
873 vascular Society consensus conference report set an acceptable risk of death or injury to other drivers at O&X%, below the reported incidence. The authors suggestthat with treatment, 90% of those with syncope can be treated, bringing the overall risk to 0.026%. They recommend that patients with frequent spells, no prodrome, and those with first presentation do not drive for three months, This recommendation is consistent with that of most states. [Edward A. Walton, MD ]
Cl UPDATE: ALCOHOL RELATED TRAFFIC FATALITlES-UNlTED STATES, 1982-1993. MMWR Morb Mortal Wkly Rep. 1994;43(47):861-3. In those between 1 and 34 years of age, traffic fatalities are the leading causeof death. In 1993,40,115 traffic fatalities occurred; 17,461 were alcohol-related. The National Highway Transportation Safety Board defines alcoholrelated traffic fatalities as deaths where a driver, pedestrian, or bicyclist had a Blood Alcohol Level (BAL) >O.Ol. Eighty percent of fatalities occur with a BAL > .lO. In the period of 1982to 1993, alcohol-related traffic fatalities decreasedfrom 25,165 to 17,461, a 31% decrease. Alcohol-related fatalities as compared to all traffic fatalities decreased from 57 to 43%. The percentage of alcoholimpaired drivers involved in fatal crashes decreased from 39 to 27%. The editors credit these decreaseson increased public awareness of the dangers of drinking and driving, more effective legislation dealing with those found intoxicated while driving, increased use of sobriety checkpoints, laws which raised the drinking age to 21 years, and overall decreasedalcohol consumption. They recommend stronger sanctions for repeat offenders, continued use of sobriety checkpoints, and increased enforcement of seat belt laws to continue these encouraging trends. [Edward A. Walton, MD]
Editor’s Comment: This is a retrospective review, but raises concerns for the evaluation of patients who are potentially preeclamptic.
0 SMOKING STATUS AS THE NEW VITAL SIGN: EFFECT ON ASSESSMENT AND INTERVENTION IN PATIENTS WHO SMOKE. Fiore MC, Jorenby DE, Schensky AE, et al. Mayo Clin Proc. 1995;70:209-13. The Centers for Disease Control have reported that fewer than 60% of smokers in the United States have ever been advised by their physician to quit smoking. Educational strategies such as lectures, conferences, and guidelines have minimally influenced physician behavior in this regard. In this prospective study, the authors surveyed patients before (N = 870) and after (N = 994) the implementation of smoking as a vital sign in an outpatient clinic setting. The survey asked whether patients were asked by the physician about their smoking status and whether they were urged to quit. A rubber stamp that included smoking status (current, former, never), as well as the traditional, was used at the beginning of the chart for each patient encounter. Medical assistants completed the vital sign portion of the chart. Patients reported being asked more often about smoking (58 vs. SlVo), being told to quit (49 vs. 70%), and being given specific advice on how to quit (24 vs. 43%) after the institution of smoking as a vital sign. All three of these criteria were statistically significant. The authors conclude that this low-cost intervention may be effective in reminding physicians to counsel their patients regarding tobacco use. An accompanying editorial notes [Christopher F. Richards, MD] that it is about time. Editor’s Comment: However, it is unlikely that the emergency department will be an appropriate environment for such interventions.
0 DO DOCTORS ACCURATELY ASSESS CORONARY RISK IN THEIR PATIENTS? PRELIMINARY RESULTS OF THE CORONARY HEALTH ASSESSMENT STUDY. Grover SA, Lowensteyn I, Esrey KL, et al. BMJ. 1995;310:975-8. This article details the results of a questionnaire survey performed in Ontario, Canada to evaluate the ability of doctors in primary care to assessa patient’s risk of coronary heart disease. Doctors from 24 selectedareas in urban and rural communities throughout Ontario, Canada were recruited for this study. During a 10 to 15 min break following a lecture on coronary health assessment,the participants were given a questionnaire which included a list of 14 coronary risk factors and two hypothetical cases. The doctors were asked to rate the importance of each coronary risk factor and to estimate the relative and absolute coronary risk of the two hypothetical patients (an “average” 30-year-old Canadian man and a IO-year-old Canadian woman). The results of the survey were compared to the
The Journal of Emergency Medicine
predictions made by the Coronary Heart Disease Prevention Model based on the Framingham Heart Study, the Canadian health survey, and Canadian life tables. Four hundred and forty-five doctors attended the meetings. Two hundred and fifty-three (57%) participated in the study and completed the questionnaire. One hundred and fortytwo doctors rated their confidence level as 3 or higher (1 being very confident and 10 not at all confident). For the 30-year-olds, doctors rated smoking as the most important risk factor and raised serum triglyceride concentrations as the least important risk factor. For the 70-year-olds, they rated diabetes as the most important risk factor and raised serum triglyceride concentrations as the least important. They rated each individual risk factor as significantly less important for the 70-year-olds than the 30-year-olds. The doctors overestimated the eight-year coronary risk for both hypothetical patients compared to the predictions made by the Coronary Heart Disease Model. Although the doctors overestimated the coronary risk, they were accurate in estimating the relative risk of the hypothetical patients compared with the age-matched and sex-matched Canadian averages. The doctors also overestimated the long-term benefits of modifying one or more specific risk factors. The authors found that experienced doctors’ assessments of the absolute risk of coronary diseasewere wrong but the assessmentsof the relative risk were correct. The authors concluded that with some recalibration and training, doctors might be able to predict accurately both relative and absolute risks. [Richard Chen, MD] Editor’s Comment: Accurately assessingcoronary risk factors may increase our diagnostic accuracy based on historical features.
0 QT DISPERSION AND MORTALITY AFTER MYOCARDIAL INFARCTION. Glancy JM, Garratt CJ, Woods KL, et al. Lancet. 1995;345:945-8. Approximately 3% of patients who suffer an acute myocardial infarction and are discharged from the hospital die of a dysrhythmic event within one year. With the advent of successful anti-dysrhythmic agents, attempts are being made to identify post-myocardial infarction patients at risk for sudden death. The authors of this retrospective study investigated the relationship of variance of QT intervals on electrocardiogram and subsequent death in patients admitted for myocardial infarction. One hundred and sixty-three patients who died between 24 hours and 61 months after myocardial infarction were compared with an age- and sex-matched group of patients who survived this period of time. The electrocardiographic (EKG) QT interval variance or dispersion was analyzed in these patients on days 2 or 3 post-infarct (the time of greatest dispersion), and at least 4 weeks later. Only 53 patients in the expired group and 82 patients in the living group had follow-up EKGs available. The QT dispersion was calculated as the difference between the longest and shortest QT intervals on an individual’s EKG. QT dispersion was then corrected for heart rate.
Abstracts
There was no significant difference in QT dispersion on early post-infarct EKGs between patients who survived and those who expired. However, the mean change in QT dispersion between early and follow-up EKGs was significantly greater in the group of patients who survived compared with those who expired. In addition to this notable difference, there were also differences in the rates of heart failure, previous infarctions, presence of bundle branch block, use of thrombolytic agents, and proportion of patients with inferior myocardial infarctions, between the patients who survived and those who died. The authors suggest that late QT dispersion may identify a subgroup of patients at higher risk of sudden death. [Christina Johnson, MD] Editor’s Comment: While the QT dispersion results are intriguing, there are a significant number of confounding variables that limit one’s ability to apply QT dispersion data in patient management at this time.
U CAN PATIENTS WITH NEUROMEDIATED ,SYNCOPE SAFELY DRIVE MOTOR VEHICLES? Sheldon R, Koshman ML. Am J Cardiol. 1995;75:955-6. Recent studies with head-up tilt table testing have shown that up to 75% of syncope is neuromediated. The authors of this study attempted to determine the risk of syncope while driving in those who have had a syncopal episode and a positive tilt table test. Two hundred and nine patients with a history of syncope who also had a positive tilt test were included in the analysis. Five patients had a history of fainting while driving a motor vehicle. Two of the.accidents resulted in injury to the driver, there were no fatalities, or pedestrian or passenger injuries. Considering these data, the authors estimate the risk per year of a syncopal episode with a resulting auto accident at 4/1,534 or 0.26%. The risk of harm was 2/l ,534 or 0.13%. The Canadian Cardio-
873 vascular Society consensus conference report set an acceptable risk of death or injury to other drivers at O&X%, below the reported incidence. The authors suggestthat with treatment, 90% of those with syncope can be treated, bringing the overall risk to 0.026%. They recommend that patients with frequent spells, no prodrome, and those with first presentation do not drive for three months, This recommendation is consistent with that of most states. [Edward A. Walton, MD ]
Cl UPDATE: ALCOHOL RELATED TRAFFIC FATALITlES-UNlTED STATES, 1982-1993. MMWR Morb Mortal Wkly Rep. 1994;43(47):861-3. In those between 1 and 34 years of age, traffic fatalities are the leading causeof death. In 1993,40,115 traffic fatalities occurred; 17,461 were alcohol-related. The National Highway Transportation Safety Board defines alcoholrelated traffic fatalities as deaths where a driver, pedestrian, or bicyclist had a Blood Alcohol Level (BAL) >O.Ol. Eighty percent of fatalities occur with a BAL > .lO. In the period of 1982to 1993, alcohol-related traffic fatalities decreasedfrom 25,165 to 17,461, a 31% decrease. Alcohol-related fatalities as compared to all traffic fatalities decreased from 57 to 43%. The percentage of alcoholimpaired drivers involved in fatal crashes decreased from 39 to 27%. The editors credit these decreaseson increased public awareness of the dangers of drinking and driving, more effective legislation dealing with those found intoxicated while driving, increased use of sobriety checkpoints, laws which raised the drinking age to 21 years, and overall decreasedalcohol consumption. They recommend stronger sanctions for repeat offenders, continued use of sobriety checkpoints, and increased enforcement of seat belt laws to continue these encouraging trends. [Edward A. Walton, MD]