Complications Associated with New-Onset Atrlal Flbrlbtle~ I read the article by Friedman’ in the Journal. The authors have addressed a significant and common problem. It would have been more meaningful if the authors would have evaluated the data according to the principles of formal decision analysis. Calculation of pertinent test measures(true-positive rate TPR, false-positive rate - FPR, likelihood ratio positive - LR+, and likelihood ratio negative LR-) Table I reveals the following individual clinical variables are good predictors of complications: current use of antiarrhythmic therapy (pathognomonic, e.g., no false positives); history of congestive heart failure (LR+ = 7.80); left bundle branch block (LR+ = 7.0); jugular venous pulse distension (LR+ = 6.50); severeleft ventricular dysfunction on echocardiography (LR+ = 4.40); and current di-

goxin therapy (LR+ = 3.70). However, no individual symptom or sign was helpful in ruling out the possibility of a complication. Left atria1 size >40 mm on echocardiography had the highest TPR (0.78) and the lowest LR- (0.39). It is doubtful clinicians would find this test useful in reassuring patients and themselvesthat future complications are unlikely. The authors state that 13 of 18 patients with complications had at least 1 of 4 findings, e.g., jugular venous pulse distension, pulmonary rales, peripheral edema, or a history of congestiveheart failure. However, they do not report combinations of other findings or the number of patients without complications who had 1 or more of these findings. I suggestthe authors review their data focusing on the following combinations: history presyncope, dyspnea and palpitations; history - previous congestive heart failure, current use of digoxin therapy, and current use of

TABLE I Use of Clinical Findings to Predict Complications Associated with New-Onset Atrial Fibrillation TP FP (n = 18) (n = 80)

TPR

FPR

29

0.11

0.36

42 14 25 46 04 22 07 00

0.78 0.22 0.56 0.28 0.39 0.61 0.33 0.11

0.53 0.18 0.31 0.58 0.05 0.28 0.09

LR+

Current digoxin therapy Antiarrhyth. therapy

02 14

04 10 05 07 11 06 02

0.00

-

1.47 1.22 1.81 7.80 2.18 3.70 Infinity

LR-

-

0.47 0.95 0.64 0.64 0.54 0.83 -

Physical Signs

Jugular venous pulse

07

05

0.39 0.06 6.50 0.65

distens. Periph. edema Rales

08 10

14 21

0.44 0.18 2.44 0.68 0.56 0.26 2.15 0.60

Laboratory Signs LBBB

05

03

0.28 0.04 7.00 0.75

CHF or edema chest x-ray

07

12

0.39 0.15

Abnormal chest x-ray Elevated CPK Elevated CPK-MB Left atrium >40 mm echo LV dysfunct. Echo Severe LV dysfunct. Echo

10

25

0.31 0.21 0.11 0.44

2.60

0.72

1.81 2.38 3.00 1.77

0.64 0.63 0.75 0.39

09

17

06 14

09 35

0.56 0.50 0.33 0.78

10 04

29 04

0.56 0.36 1.56 0.69 0.22 0.05 4.40 0.82

CHF = con estive heart failure; CPK = creatinine phosphokinase; distens. = Echo = echacardiography; FP = false positives; distension; d J unct. = dysfunctional; FPR = false-positive rate; LBBB = left bundle branch block; LR+ = likelihwd ratio vtF;LR=,,’ Ilk&hood ratio ne g tive; LV = left ventricular; TP = true positives: r of patients with complications asscxiated with PR true poslbve rag: 18 = num new-onset atrial fibrillabon; 80 = number of patients without complications associated with new-onset atrial fibrillation.

842

Portland, Oregon 30 April 1991

1. Friedman HZ, Goldberg SF, Bonema JD, Cragg DR, Hauser AM. Acute complications associated with new-onset atrial fibrillation. Am J Cardiol 1991;67: 437-439. 2. Nardone DA, Roth KM, Mazur DJ, McAfee JM. Usefulness of Physical Examination in Detecting the presence or absence of Anemia. Arch Intern Med 1990;150:201-204.

History Presyncope Dyspnea Palpitations Fatigue Nausea or vomiting CHF Smoking

antiarrhythmic therapy; physical examination - jugular venous pulse distension, peripheral edema, mitral regurgitation murmur and pulmonary rales; and laboratory data - left bundle branch block and congestive heart failure on chest x-ray. One can assume that the TPR would increase significantly and the LR- would decrease significantly if only 1 finding of the combination was required to be present (rule out the possibility of a complication); and conversely the FPR would decrease significantly and the LR+ would increase significantly if all findings of the combination were required to be present (confirm the likelihood a complication will occur) (Table II). This technique has beenusedin a similar study.2 No doubt the results from such an analysis by Friedman et al would be more helpful at the bedside than the data presentedin their original article. DavidA. N~~DIw, MD

THE AMERICAN JOURNAL OF CARDIOLOGY VOLUME 69

TABLE II Use of Combination of Findings to Predict Complications Associated with New-Onset Atrial Fibrillation

Best for predicting complication(s) will not occur Presence of 1, 2 or 3 (at least 1) findings of the combination None of the findings of the combination present Best for predicting complicationW will occur Presence of all findings of the combination None, 1 or 2 of the findings of the combination present

MARCH 15. 1992

Complication(s) from New-Onset Atrial Fibrillation (n = 18)

Lack of Complications from New-Onset Atrial Fibrillation (n = 80)

True positives

False positives

False negatives

True negatives

True positives

False positives

False negatives

True negatives