Transthoracic Doppler ultrasound coronary flow reserve evaluation: preliminary insights into pathophysiology of Takotsubo cardiomyopathy

Abstract

The aim of this study was to elucidate the role of coronary microvascular function in the pathophysiological scenario of Takotsubo cardiomyopathy. Noninvasive evaluations of coronary flow reserve through transthoracic Doppler ultrasound imaging of the left anterior descending coronary artery, a reliable marker of coronary microcirculation performance in the absence of epicardial coronary artery stenosis, were performed both in the acute and recovery phases of Takotsubo cardiomyopathy in consecutive patients strictly selected on the basis of absence of risk factors, concomitant diseases, or both impairing coronary microvascular function. Resting and hyperemic diastolic flow velocity tracings and corresponding velocity time integrals were obtained in seven consecutive patients, six of them women, aged 65-86 years (76 +/- 6.5) at admission and 23 +/- 4 days after, when left ventricular wall motion alterations recovered. In addiction, thrombolysis in myocardial infarction frame count of the two branches of the left coronary artery was evaluated on the cineangiogram obtained at admission. It was normal in both branches of the left coronary artery (left anterior descending, 30.6 +/- 8.79; circumflex, 23.4 +/- 2.96). In each patient, coronary flow reserve, calculated both on velocity time integrals (2.6 +/- 0.2) and average peak diastolic blood flow velocity (2.48 +/- 0.1) values, was in the normal range (>2.0) and did not significantly change when reevaluated in the recovery phase (2.55 +/- 0.1, 2.44 +/- 0.1). These data suggest that coronary microvascular function may not be impaired in Takotsubo patients when negative influences on coronary flow reserve by concomitant diseases and coronary risk factors are excluded. Its noninvasive evaluation with transthoracic Doppler ultrasound of the distal left anterior descending appears simple and useful in this type of patients.