Publications

OBJECTIVES

This study compared a biphasic waveform with a conventional monophasic waveform for cardioversion of atrial fibrillation (AF).

BACKGROUND

Biphasic shock waveforms have been demonstrated to be superior to monophasic shocks for termination of ventricular fibrillation, but data regarding biphasic shocks for conversion of AF are still emerging.

METHODS

In an international, multicenter, randomized, double-blind clinical trial, we compared the effectiveness of damped sine wave monophasic versus impedance-compensated truncated exponential biphasic shocks for the cardioversion of AF. Patients received up to five shocks, as necessary for conversion: 100 J, 150 J, 200 J, a fourth shock at maximum output for the initial waveform (200 J biphasic, 360 J monophasic) and a final cross-over shock at maximum output of the alternate waveform.

RESULTS

Analysis included 107 monophasic and 96 biphasic patients. The success rate was higher for biphasic than for monophasic shocks at each of the three shared energy levels (100 J: 60% vs. 22%, p < 0.0001; 150 J: 77% vs. 44%, p < 0.0001; 200 J: 90% vs. 53%, p < 0.0001). Through four shocks, at a maximum of 200 J, biphasic performance was similar to monophasic performance at 360 J (91% vs. 85%, p = 0.29). Biphasic patients required fewer shocks (1.7 +/- 1.0 vs. 2.8 +/- 1.2, p < 0.0001) and lower total energy delivered (217 +/- 176 J vs. 548 +/- 331 J, p < 0.0001). The biphasic shock waveform was also associated with a lower frequency of dermal injury (17% vs. 41%, p < 0.0001).

CONCLUSIONS

For the cardioversion of AF, a biphasic shock waveform has greater efficacy, requires fewer shocks and lower delivered energy, and results in less dermal injury than a monophasic shock waveform.

To improve tobacco-control efforts by applying tobacco-industry marketing research and strategies to clinical and public health smoking interventions, we analyzed previously secret tobacco-industry marketing documents. In contrast to public health, the tobacco industry divides markets and defines targets according to consumer attitudes, aspirations, activities, and lifestyles. Tobacco marketing targets smokers of all ages; young adults are particularly important. During the 1980s, cost affected increasing numbers of young and older smokers. During the 1990s, eroding social acceptability of smoking emerged as a major threat, largely from increasing awareness of the dangers of secondhand smoke among nonsmokers and smokers. Physicians and public health professionals should use tobacco-industry psychographic approaches to design more relevant tobacco-control interventions. Efforts to counter tobacco marketing campaigns should include people of all ages, particularly young adults, rather than concentrating on teens and young children. Many young smokers are cost sensitive. Tobacco-control messages emphasizing the dangers of secondhand smoke to smokers and nonsmokers undermine the social acceptability of smoking.