Background: Cardiovascular and cerebrovascular disease is 2-3 times more common in bipolar patients than the general population. Asymptomatic bipolar patients have electrocardiogram abnormalities at high rates. The question of heart function in asymptomatic bipolar subjects arises.
Methods: This study examined the impact of exhaustive exercise on cardiac function in untrained euthymic bipolar and control subjects. Twenty-four non-athletic adults, 10 controls and 14 with bipolar type I, exercised on a treadmill at 70% of maximal oxygen consumption until physical exhaustion. Two-dimensional and Doppler echocardiography were performed before and immediately after exercise.
Results: Bipolar subjects had significantly reduced exercise duration (75.9+/-40.5min for bipolar and 95.0+/-40.1 min for control, P<0.01). There were no statistical differences between bipolar illness and normal controls in echocardiographic variables either at rest or after exhaustive exercise.
Conclusion: Medically asymptomatic, euthymic bipolar subjects appear to have reduced exercise tolerance but normal cardiac function.
Limitations: More bipolar patients smoked (28.6% vs. 0% controls) and patients tended to be heavier (189.1+/-29.3 vs. 165.0+/-29.5 lb, t=2.0, P=0.06). None of the normal controls were taking any medications. These variables could have impacted the reduced exercise tolerance.